


Tartarus Gate

by secooper87



Series: The Child of Balime [60]
Category: Buffy the Vampire Slayer, Doctor Who, Doctor Who & Related Fandoms
Genre: Action/Adventure, Crossover, Family, Mystery
Language: English
Status: Completed
Published: 2015-06-04
Updated: 2015-06-19
Packaged: 2018-04-02 19:30:32
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 12
Words: 21,620
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4071928
Author URL: https://archiveofourown.org/users/secooper87/pseuds/secooper87
Summary: <blockquote class="userstuff">
              <p>As the Doctor, Jack, and Seo all gather on Ariffildos, Buffy — still stuck outside the universe — struggles to save them all.  But everyone has their greatest fears…</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> Second to last story in the series! I'm working on perfecting the first story in my next series, "Shockwave Vampires." More updates on this, later. (This next series will work a little differently. It will be available for free online, but if you wish to read it all at once or download it onto a mobile device, you may do so for a small fee on Kindle. I'll give more updates as we get closer.)

Clara shrieked, as she stumbled, and the Doctor grabbed her by the arm and pulled her to her feet. Then ducked, to avoid a blast from a laser pistol.

"Does every trip have to involve people shooting at us?" Clara cried, as they began sprinting, again.

"What? No!" The Doctor fished around in his pocket, for the TARDIS key, as the blue box came into sight, ahead of them. "Most of my trips are cool!"

He fitted the key into the lock, Clara jumping out of the way of the next blast of firepower, as the Doctor opened the door for Clara, who raced inside.

But… the Doctor, paused, just for a second.

Licked his index finger, then held it up in the air. "Curious…"

"Doctor!" Clara shouted. Grabbing him by his jacket and dragging him into the ship, just before the next laser blast hit him. "Get in!"

The Doctor found himself a tangle of limbs and Clara, on the TARDIS floor, as they both fell inside and the doors snapped shut.

"Very curious," the Doctor said, his face still bent in a frown — as if Clara had never interrupted him. He looked down at the index finger he had licked. The frown deepening. "And very wrong."

The sound of lasers hitting the outside of the ship reverberated through the console room.

"Doctor!" Clara hissed, getting him up off the ground.

The Doctor blinked. Snapping out of his reverie. "Yes? Oh, right!" He lunged for the central console. "The escape!"

The TARDIS engines roared into life, as Clara tried to catch her breath from their last sprint-for-their-lives. The Doctor, as if the bit with his index finger had never happened, began chatting happily about the whole ordeal.

"That's the thing about nasty dictators," the Doctor was explaining, while dancing around the console and choosing where to go next. "They're bullies. Moment they realize you've overthrown them and made them powerless, they start chasing you down with guns." He flipped three switches, with a flourish. "Now! Iced cream!"

Clara managed to stop gasping for air long enough to shoot him a look. "Iced cream?"

"Planet Gilmaw, 94th century!" the Doctor agreed. "Best iced cream you'll ever taste. And no guns. How about that?"

His cheery disposition flickered for just a hint. Then, suddenly, going back to normal.

"Is this you trying to ask me on a date, chin-boy?" Clara asked.

"What?" the Doctor looked up, flustered. "No! I just…"

He noticed the mischievous look in her eye, and realized she was teasing.

"Oh, shut up," the Doctor muttered, slamming them into materialization.

* * *

"…of course, the peppermint's the best," the Doctor was explaining, as he opened the doors and stepped out of the ship. He looked back over his shoulder, at his companion. "Oh, except if you want to be adventurous, and try Gazonga Swirl." He licked his index finger, and held it up in the air, again. "Now. That isn't what I expected—"

"Doctor?" Clara interrupted.

Pointing at the landscape beyond the doors.

The Doctor turned back around. Then froze. And stared.

All around him, where he knew there should be a vibrant marketplace, he saw only ruins. Dust. Debris. Not a single sign that life had been present for many, many years.

"Ah," said the Doctor. Looking back at his index finger, then at the landscape around him. "That explains it."

"Explains what?" Clara asked. "Did you land us in the wrong time and place, again?"

The Doctor pointed at any enormous ruined stone fountain, dominating the center of the marketplace. "The Great Fountain of Gilmaw," he said. "Can't miss it. Fountain jets used to shoot up higher than any other fountain in the universe. One of the wonders of the galaxy." He threaded his fingers together. "No, this is Gilmaw. And the air tastes like the 94th century."

"Tastes like…?"

The Doctor spun back around, and raced into the TARDIS.

Clara running after him, the doors shutting behind her, as the Doctor launched them back into the vortex.

And then landed, again.

Popping his head out the doors.

"Just what I thought," the Doctor said. Opening the doors a little wider, so Clara could see. "The collapse of an artificial time façade."

"An artificial time… what?" Clara looked out the doors.

And stared.

The rubble and ruin she saw, out the doors — no sign of anyone alive — was the exact same planet they'd just left, after toppling that dictator and running away from a bunch of gun-toting guards.

"What happened, between when we left and…?" Clara asked.

"Nothing," said the Doctor. "We landed one second after we left this planet." He gestured outside. "But… as you can see… it's been in a state of ruin for at least a century."

Clara shook her head. "How's that possible?"

The Doctor turned to run back into his TARDIS. "I said — the collapse of an artificial time façade." He pulled a lever, and checked a readout on the scanner. "I sensed the façade, just before we hit the TARDIS, when we were running from those nasty guns. But now… seems whatever was generating it has been destroyed." He waved at the doors. " _This_  is what the planet really looks like."

"But why?" said Clara. "What destroyed it? Was it those Firgo Terrorists?"

The Doctor tapped something into the TARDIS, checked the scanner screen. Shook his head.

"Nothing," he told Clara. Glanced over at her. "This planet was just… destroyed. For no reason."

The look on his face made Clara shudder.

"Oh, but it gets worse." The Doctor threw the TARDIS into motion, again, and — seconds later — landed on another planet.

Stuck his head out the door.

"Dead," the Doctor said, looking at the lifeless ruins around him. The overgrown weeds all across the crumbling city. "Nothing. No life."

Clara stuck her head out the door, too.

"And no reason why this one was destroyed, either," the Doctor said. "Or no central cause that might help us, at any rate."

"That doesn't make sense," Clara said.

The Doctor sprinted back to the central console. Kept plugging in planets in the distant future — planets he  _knew_  should still be there! Planets from all across the universe! And every single time he checked…

"No life," the Doctor cried, on his tenth destroyed world. "No nothing."

Clara stood beside him, in the middle of the desolation.

"But… that's not supposed to happen, right?" Clara guessed. "This many planets don't just… disappear or become lifeless for no reason."

"No, it's not," the Doctor agreed. He brushed his floppy brown hair out of his eyes. "Something must have happened, in the past, to change the history of the universe. Drastically." He poked at some more buttons on the console. "And whatever happened… it's destroyed the future."

* * *

"But what kind of disaster could destroy half a universe?" Clara asked, as the Doctor raced around the central console. "And wipe out life in a lot of the rest of it!"

"Something big," the Doctor guessed, flipping at switches and poking at buttons. "Something huge!" He spun around, then pressed some more buttons on the panel behind him. "A great big gigantic something that made a whole bunch of others somethings either happen or not happen — depending on your point of view."

"You don't know, do you?" Clara guessed.

The Doctor didn't answer.

Clara cringed, as a nasty thought entered her head. She stepped forwards, grabbed the Doctor's hand. "This… isn't because of us, is it?"

The Doctor looked up at her.

"Well…  _we_  did a big thing, right?" Clara prompted. "With… Gallifrey?"

The Doctor's eyes went dark. And he yanked his hand away.

"No," he insisted, turning away from her. "Couldn't be. They… they'd be peaceful, this time around. No more Final Sanction or…"

He trailed off.

His face growing more and more worried, by the second.

Then he pasted a smile on, and returned to the central console. "Right! Time to take you home! End of the adventure!"

"What?" Clara cried. She put her hands on her hips. "You can't just leave me behind."

The Doctor didn't answer.

"If this is about Gallifrey, it's as much my fault as it is yours!" Clara insisted. "I want to help!"

"It's nothing to do with Gallifrey," the Doctor dismissed. He waved her suspicions away with his hand. "If the Time Lords had done this, the destruction would have looked completely different. Believe you me!"

The TARDIS materialized outside of Clara's house.

"Which means I have to go off and do all the boring research bits," the Doctor continued, running over to open the door for her. "And I know you'd hate that. I'll be back and pick you up when we get to the good part."

Clara hesitated.

"I'm not just leaving you behind," the Doctor insisted. "Really! Be back in two shakes."

Clara finally gave in. Figured — from the baffled look on his face — that he really  _didn't_  think this was because of Gallifrey. And really  _did_  need to do research to figure out where and when this was.

"Two shakes," Clara reminded him, as she left. "I'm holding you to that!"

* * *

The Doctor waited until Clara departed the TARDIS.

Then raced back to the central console, dematerialized, and began typing furiously. Trying to get a pinpoint on where, exactly, everything in history had begun to go wrong.

"Ariffildos," the Doctor read off the scanner. "On the 8th of Waget, 983 — according to the Veringan chronology. Which no one in their right mind can figure out how to use." He grinned to himself. "32nd year of the reign of my good friend, King Bob! Hope he remembers me."

He programmed the coordinates into his TARDIS.

Then pulled the materialization lever.

"Time to work out what changed history!" the Doctor announced.


	2. Chapter 2

Buffy flew through the air, spinning around so she delivered another kick to her assailant. He groaned, the knife falling from his hands.

"Just because I don't have a gun," Buffy said, coming over to him and grabbing the paper notes from his hand, "doesn't mean I'm helpless."

She returned her money to her pocket.

And went on.

The problem with trying to get out of the Tartarus Gate, Buffy had realized, was that it was both impossible and illegal.

"This gate is secret," one of the wretches she dealt with had explained to her. "Not even the Time Lords knew of its existence, back when they were alive."

Apparently, opening the gate would let everyone in on the secret that it existed.

So they tried to avoid it.

Buffy headed off to one of the sketchiest bars she'd ever seen — which was saying something — went in, and noticed her contact, at the booth.

She slid in, opposite him.

Handed him the money.

"Fifty immortal souls," Buffy said. "You can make a lot working as a bodyguard around here."

The contact — a mysterious black-looking entity in a dark cloak, whose voice sounded like death — took the money. Counted it. Then slipped the notes into his cloak.

"Cough up," Buffy snapped.

The contact said nothing.

"I need a way out," Buffy demanded. "You said you could get one for me." She leaned down, her voice turning icy. "You gonna tell me? Or I'm I gonna have to get Slayer on your ass?"

"There are… people," the contact whispered, "who are interested in you."

Yeah.

Because  _that_  didn't send shivers down Buffy's spine.

"What kind of people?" Buffy asked. "And what kind of 'interested'?"

The contact went silent.

Okay.

Clearly, that information required more than 50 immortal souls.

"Just answer me this," Buffy requested, her voice very low. "Can they get me out the Gate?"

"Not exactly," said the contact. He sipped at his drink. "But they can let you save those on the other side of it."

Buffy went very still.

"How?" she whispered.

No answer.

"Okay, okay," Buffy muttered. She checked her pockets, but she was clean out of money. Sighed. "How many immortal souls is this gonna cost me?"

"If you let me lead you to them, it costs nothing," the contact replied. " _They_  will pay me. If you want information, first… a hundred and forty."

"A hundred and…?!" Buffy shook her head. "Okay! Fine! Let's go with the cheap option."

The contact got up from the table. Beckoned for her to follow, as he drifted across the floor and out the front of the bar. Buffy was getting a worse and worse feeling about this, as the contact got out a gigantic gun to protect himself as he led her down and down into the bowels of this place.

He paused, in front of a big metal door.

And knocked out a code-rhythm.

A long pause, as the peephole slid open, just a crack. Then the sounds of locks being pulled aside, and the door pulled open.

A large, red-horned demon standing behind it.

"So this is her?" the red-horned demon asked. "Buffy Anne Summers?"

The contact slid aside, gesturing at the Buffy. "She says she's willing."

"Whoa — I said I was willing to  _meet_  these guys," Buffy countered, stalking up to them, ready to fight at a moment's notice. "I'm not deciding anything, yet, until I get more details."

The red-horned demon nodded, with a wide grin.

"You have done well," the red-horned demon told the contact. He slipped a five hundred note out of his pocket, handed it to the contact. "Your payment. Now leave."

The contact, in a puff of smoke, vanished.

Leaving Buffy alone with the red-horned demon.

"Come in, Summers," the red-horned demon requested. Gesturing inside. "We have been awaiting you."

Buffy stayed her ground.

"Details, first," Buffy demanded. "You can't open the Gate, right?"

The red-horned demon shook his head. "But we  _can_  let you save your friends," he told her. "Despite your being stuck outside the universe."

"How?" Buffy demanded.

"By playing our game!" the red-horned demon laughed. "All the game-pieces have gathered — Jack, the Doctor, your daughter. The board's been set up at the turning point of history. And you — Buffy Summers — will play."

Turning point of… history?

Buffy didn't like the sound of that.

"Thanks, but no thanks," Buffy said, turning around to head off. "I'm not screwing with any 'turning points of history' or whatever. If the Doctor's there, he'll deal with it."

"The Doctor saves history, yes," the red-horn demon replied. "But will he be able to both save history… and save your daughter?"

Buffy froze, in place.

"You are a hero, too," the red-horn demon continued. Crossing his arms, in the threshold. "You know — heroes always have to make sacrifices. And sometimes, try though they might — they can't save everyone."

Buffy spun back around.

"But  _two_ heroes…" the red-horned demon told her, with a wink.

"Who are you?" Buffy said. Taking a tentative step forwards. "What are you? And how are you going to be able to save her?"

The red-horned demon waved her in. "Come and meet the gang!"

* * *

"Doctor!" said the old and wise King Robert Hennor IV, as he stood from his throne and embraced the Time Lord. "Here am I, so aged and withered — yet you appear not to have aged a day from when I last saw you!"

"Oh, but you look splendid!" the Doctor said. "I like the jewels in the robe — very posh." The Doctor stepped back, twirled his sonic in his hand. "But, actually, your highness, came here to see about a teensy weensy little wrinkle in time. Tracked it down to about this spot. Wanted to make sure I could stop it."

King Bob sighed. "There always is trouble when you're around, isn't there?"

"I'm looking for something… out of the ordinary," the Doctor proposed. "Anything to indicate temporal interference. Anyone around here who's just a little out of place. I checked around with the locals, and they all said—"

"That there were two strange people who appeared from nowhere, who are now locked in my dungeons," King Bob said. "Yes, Doctor. And they really are a nuisance. They keep escaping."

The Doctor waggled his sonic. "Do they?"

"Escaping, then racing back to the scene of the crime, again," the King continued. "We catch them. Lock them up. And they escape. And return. It's growing tiresome."

An angry shout, from just outside the throne room.

And the King sighed, again.

"That's them now," the King said. "Seems they've escaped and been dragged back, yet again."

The doors to the throne room flew open.

And a large group of guards strode in.

"Your majesty," said one of the guards, struggling to restrain the prisoners. "We found these two back at the crime scene, trying to—"

"Jack!" the Doctor cried. "Seo!"

"Father!" Seo shouted, managing to break free from the stunned guards and rush forwards. She swept him into a tight hug. Then pulled away, a little wary. "Did you follow me here?"

"Actually, I followed the time anomaly," the Doctor replied. "Superimposed artificial timeline that got stripped away, revealing that the future's been destroyed." He caught the flush on Seo's cheeks. "You wouldn't happen to know anything about that?"

"No," Seo said, quickly.

Jack sighed, trying to tuck his thumbs under his suspenders — but the guards tightened their grips on him. "We found a trapped hell goddess, going on a murder spree," he said. "Seo felt sorry for her and sent her home. Thus, destroying the universe."

The Doctor gave Seo an intrigued look.

"Um… sorry?" Seo tried.

The Doctor spent another minute, just giving her that look.

Then clapped her on the back. "Well," he said. "At least, if you've destroyed the universe, you still came back to try to un-destroy it." He leaned in, conspiratorially. Whispered, "So. What are we facing, here?"

"A wave of horrible murders on this planet," Seo whispered back to the Doctor. "Jack and I keep trying to figure out what caused them…" She raised her voice to a shout. "…but every time we do, the King keeps having us arrested!"

The King, from his throne, cleared his throat.

The Doctor spun around, realizing that he probably should explain things a bit better. "Ah, yes, your majesty!" He stepped forwards, an arm draped around Seo's shoulders. "May I introduce… my… well…" He hesitated, looking down at Seo.

Seo looked back up at him.

"…suppose you could call her my daughter," the Doctor said. Shrugged. "Not exactly. But close enough."

"Close enough?" Seo hissed.

The Doctor ignored her.

The King stroked his long, gray beard. "I see," he said. Gestured at Jack. "And the other?"

"A friend," said the Doctor. "Used to travel together. Now he's looking after Seo." He glanced down at Seo. "He…  _has_  been looking after you, right?"

Seo shrugged. "I look after him."

The Doctor grinned, figuring that — with Seo's pride and all — this was as close to a 'yes' as he was going to get.

The King was quiet for a very long time. Then, in a darker voice, he added, "What your friends failed to mention to you, Doctor, was that the murders only began the moment they arrived. And have always happened when they're outside the confines of my dungeons."

"Yes, but that doesn't mean we killed those people!" Seo cried. "We're just trying to find out what happens, on this planet, that will destroy half the—!"

The Doctor shushed her.

Then returned to his good friend Bob. "Tell you what, Bob! I'll take them under my wing. Make sure they don't get up to any mischief. And — while I'm at it — I'll sort out the murders for you. How's that?"

Bob seemed hesitant.

But, with another heavy sigh, conceded.

"After you saved our entire world, last time you were here," Bob said, "I can hardly deny you the chance to do it again."

"Splendid!" The Doctor whirled around, to collect Jack. "Now, you two. Take me to see these 'mysterious murders'."


	3. Chapter 3

Buffy walked into the room, to find two other red-horned demons bent over a table, staring in delight at the center of it.

Just above the center of the table floated an image of three figures, all a universe away from her, separated by the Gate. The three walked down an alleyway.

Buffy recognized them.

"Seo!" Buffy raced over, her hands against the tabletop. Her eyes lingering on the image. "You're alive." She felt her breath catch in her throat. "Oh, thank God, you're…!"

One of the red-horned demons coughed, pointedly.

And Buffy looked up.

"She is, now," said the red-horned demon. "But this is just the beginning."

Buffy's blood went cold. "What do you mean?" She stepped back. Crouching into a fighting position. "And who are you? How can you claim to affect the outside universe? And… and… why do you have an image of Seo?!" She pointed to it. "She shouldn't even show up on your… video-tape thing!"

"It's not video tape," the red-horned demon behind her replied.

"We are the Havchornom," said another red-horned demon. "Our magics see all."

"Our manipulation alters all," said the third red-horned demon.

Buffy nodded, slowly.

"Except the Gate," Buffy pointed out, "which you can't open. That's why we're here, and they're there."

The Havchornom all just shrugged.

"Okay, fine," Buffy said. Gathering up her strength. "So you can screw with stuff in my universe." Her voice lowered. "Why did you want me?"

"We felt your fear," said the Havchornom behind her.

"You fascinate us," said the second Havchornom, folding his clawed hands along the table. "You fight and fight and won't ever give up. You brave years of traveling from one hell dimension to another — all because of your feelings for this child."

"A child not technically your own," the third Havchornom added.

Buffy wasn't fazed by this.

She couldn't count the number of demons who'd tried to convince her that Seo should mean nothing to her — just because Seo wasn't technically born in the same reality as Buffy. Usually, the accusation came with lots of whipping and tortures and demons trying to break down Buffy's spirit.

No one could.

"It doesn't matter where she came from," Buffy replied. "Or how she was created. Or that I'm not technically the version of Buffy who gave birth to her." She shrugged. "She's the only daughter I'll ever have. She's kind and brilliant and wonderful. And even if she made a mistake that condemned me to Hell — I still love her. I'll never stop."

The Havchornom seemed utterly bored with her love.

In Buffy's experience, most hell demons were.

"But back to the matter at hand," one of the Havchornom pushed on. "You. Buffy Summers. You defeated Daleks for her. You impaled demons for her. You struck down the nastiest hell could throw at you — all because of  _her_."

"It's fascinating," another Havchornom agreed. "Truly fascinating."

"We can't quite work out why," the third Havchornom put in.

Buffy gave a dry laugh. "You've obviously never been a mom."

Buffy thought back to what Jack, at Torchwood, had told her — about the events that had transpired when she'd been running after Billy, trying to rescue her daughter, and the Daleks had moved the Earth to the Medusa Cascade.

Jackie Tyler, apparently, had broken through the walls of reality because her Rose was out there — and Jackie needed to protect her Rose.

Buffy got that.

Totally.

"She condemned you to Hell," a Havchornom reminded her.

"She made a mistake," Buffy corrected. "And I'm sure she went mega-guilt-trip when she found out." Buffy needed to find her and snap her out of that one, fast as possible. She crossed her arms. "But she's still my daughter. And I still love her."

"You have forgiven her," said the Havchornom behind her. "Yet you still suffer for her."

"You believe in her," said one of the Havchornom at the table, "yet you still fear for her."

"If you think so highly of her," said the other Havchornom at the table, "then surely you think she can take care of herself. Why are you in such a rush to rescue her?"

Buffy watched the image in the center of the table.

The Doctor, Seo, and Jack had entered a shop that had been smashed to hell. Three dead bodies, lying on the floor. They looked like they'd been clawed up pretty viciously.

The Doctor was waving his sonic over the body.

He was the Doctor with the big chin and floppy hair and bow tie — the one that Buffy hadn't seen for at least ten years. Maybe longer.

Just seeing him again was enough to bring a smile to Buffy's lips.

"Don't you trust the Doctor to look after her?" one of the Havchornom barked at her.

"Don't you trust Jack to save her?" another added.

"Your sister, Dawn?" the third agreed.

"Do you have so little faith in your friends that you feel the need to brave any evil in the universe to rescue your daughter?" the Havchornum asked, in unison.

Buffy didn't look away from the image in the center of the table.

Watching as the Doctor looked up at Seo, saying something about a bizarre energy reading while throwing in lots of sciency, technical terms.

And Seo chiming in her two cents with dramatic hand gestures and a bounce in her step that Buffy had missed — more than anything.

"Why won't you answer!" the Havchornom demanded.

"Because they were stupid questions to begin with," Buffy retorted. She gestured at the image at the center of the table, the smile on her face widening. "I mean… just look at her. My wonderful, beautiful, amazing Seo."

She'd been so desperately scared that she'd never see Seo again.

And here she was.

Acting… just as she always did.

"If I could just tell her I forgive her," Buffy said, mostly to herself. "Make sure she knows it wasn't her fault…"

"But what would you do to save her?" the Havchornom cut in.

Buffy looked up at them.

"The one with the Sunglasses destabilized history," said one of the Havchornom at the table. "When history settled, things weren't quite as they should be."

"The Doctor, Jack, and Seo have all come to Ariffildos," one of the Havchornom at the table explained, waving at the image, "tracking down the great catastrophe that altered time. Great harm lurks in your daughter's future."

Buffy's mouth went dry.

As her eyes lingered on Seo, in the center of the table.

"Perhaps… it will be your interference that causes the catastrophe," the Havchornom behind her supplied.

"Or perhaps it'll be your non-intervention that causes it," said the last Havchornom, at the table.

Buffy swallowed, hard.

"You're asking me to gamble with time and history," Buffy said, "so I can save my daughter's life."

The Havchornom grinned at her.

Their teeth pointy and gleaming in the artificial light.

Buffy bit her lower lip. Trying to think it all through. The Doctor was there — he knew about temporal stuff! Surely the Doctor could both figure this all out and protect Seo, at the same time.

Plus, bonus. Jack was there!

Jack would throw himself in front of the monsters before he let anything hurt Seo.

…but what if she was wrong? What if they had to choose between Seo and the rest of the universe, and decided on the rest of the universe? What if they couldn't stop Seo from doing something stupid and suicidal — and Buffy wasn't around to save her?

(Jack had told Buffy about the Valiant. Both the Doctor and Jack had been there when Seo threw herself off the edge, to prevent the Master from getting his hands on the weapon in her head. They hadn't stopped her, then.)

"Seo's death is never 'winning'," Buffy whispered to herself.

"Then you choose to get involved?" the Havchornom behind her asked, stepping forwards.

Buffy didn't answer.

Couldn't.

As she watched the image before her.

* * *

"…no, that's what I've been trying to tell you!" Seo insisted, practically dragging her father out of the shop. "They're  _not_  all like this. Every murder is different!"

"Last murder was a Wixel blaster shot," Jack added. "Right in the back."

"And the one before that was definitely a Cyberman," Seo said. "I could tell."

The Doctor's brow furrowed. He pointed back at the shop. "That wasn't a Wixel or a Cyberman."

"Yes, we know!" Seo agreed. "That's what we're saying. We're looking for a monster that… collects other monsters. Or maybe a shape-shifter! Or maybe…!"

A scream, from not far away.

Everyone spun on their heels, towards it.

Then darted off, fast as they could, towards the sound.

"Seo, stay there, with Jack," the Doctor said, adjusting his sonic as he ran. "See if you two can find any more…"

He stopped, as he arrived at the alleyway. Discovered a huge wolf-like creature with bright blue fur, as it mauled its latest victim. The creature's howls echoing through the alley.

It stopped, as it smelled the new arrivals.

Then turned around, to face them.

* * *

Buffy watched it all unfolding, before her.

The blue furred wolf turning on the Doctor, Seo, and Jack — just running in behind them. Almost drooling at the prospect of the kill.

"What is it?" Jack asked.

"No idea," the Doctor replied, trying out a frequency on the sonic.

Buffy bunched her hands into fists. "It's a Yixolpot!" she shouted. She'd faced them down in her hell dimension adventures. "And they're deaf — sonics won't help! You need to stab them behind their left ear!"

But the people in the image playing out before her couldn't hear, either.

The Doctor's sonic screwdriver failed.

And the Yixolpot leapt forwards towards them, fangs bared and claws outstretched…

"No!" Buffy screamed.

Jack leapt in front of the Doctor and Seo, his body crunching as the Yixolpot snapped its jaws around his mid-section.

The Doctor grabbed Seo by the wrist and shouted at her to "Run!"

Buffy watched as they darted off, fast as they could, away from the Yixolpot. But the Yixolpot had already discarded Jack, and was heading for Seo and the Doctor. Seo looking behind, with a small squeak, as she saw the creature gaining…

"I can't…!" Buffy shook her head, trying to convince herself this was a bad idea.

The Doctor knew temporal stuff — she didn't! If she interfered, she could completely screw everything up! She could…

The Doctor just barely wrenched Seo out of the way of the swipe of the creature's claws.

And Buffy decided.

"I'm ready," Buffy told the Havchornom. She turned to them all. "Whatever you can do to allow me save her… just do it!"


	4. Chapter 4

"I'm ready," Buffy told the Havchornom. She turned to them all. "Whatever you can do to allow me save her… just do it!"

The Havchornom all grinned, wickedly.

And — in a flash — Buffy found herself being transported to… somewhere else. An enclosed room with white walls, a white ceiling, and a white floor. She frowned, but then the walls and floor and ceiling began to change, the image she'd been seeing now superimposed on top of it, like a living hologram.

Except… Buffy realized… she could touch this one.

As she ran, the landscape around her shifted in the direction of her running. Like some complex simulated reality. Buffy hurled herself at the Yixolpot, just as it reached out for Seo again.

Flipped through the air, pulling out a concealed dagger she'd kept on her since arriving in the area outside the Tartarus Gate.

She missed landing on its head, but instead grabbed the fur on its back, using it to catch herself and yank herself back onto the monster's body.

Then plunged in her knife — a warning.

* * *

The Doctor saw monster narrowing in on Seo. Curious that it should always go for Seo, specifically… even when it had Jack in its jaws, it still discarded him in order to go after  _her_.

"Maybe it's sentient," the Doctor proposed. Brain whirring, fast. "Or well trained. Could be someone knew she'd be here, at this point in time, and specifically wants  _her_."

This suggested to the Doctor that he should stop running and let the monster take them to its leader — but, truth be told, he wasn't completely sure that would result in Seo's remaining alive.

Or his coming with her.

Best handle this with care.

"It wants  _me_?" Seo sighed, irritated. Then, over her shoulder, shouted, "Everything in the universe wants me!  _Get in line_!"

The monster lunged for her.

And the Doctor shoved her back behind him, whirling around to stand in place directly in front of the creature, and trying the sonic again. "Take me to your leader!" the Doctor demanded.

To his surprise, the monster reared back.

Howling in agony.

The Doctor looked between the monster and the sonic. Impressed. "Right setting must make all the difference," he decided. Blasted the beast again, and it reared up, clawing at the air as if it were possessed.

"Maybe it's deaf!" Seo proposed. "It never detected us based on sound, after all; it just kept sniffing! Perhaps the sonic vibrations rattled that sense of balance located in the inner ear?"

The Doctor beamed down at her. "Good thinking! Like it." He stepped forwards. "Let's make sure."

Seo gave an irritated huff at this.

The Doctor brushed it off.

"Now that I've got your attention," the Doctor said, stopping the sonic. He bounced on his toes, in front of the creature. "Let's start with the basics. I'm the Doctor!" He gestured his sonic at Seo. "She's Seo."

She gave another huff.

"But you already knew that," the Doctor said, turning back to the creature. "So. What are you doing, here, who are you working for, and…" He opened up his hands. "Take me to your leader!"

* * *

Buffy stuck the dagger between her teeth, climbing up the monster's back by clutching at different patches of fur. It reared back, claws scrabbling at the air, trying to shake Buffy off.

But she kept on climbing, towards the head.

She could hear Seo, in the background, explaining to the Doctor that she thought the monster was deaf. Buffy grinned.

Oh, go Seo!

Then came the Doctor, stepping forwards and introducing himself to the creature. Like he thought it could hear and understand him, and had the capability for intelligent thought.

No, Doctor!

Was this what he was like without a Buffy around to give him some common sense?!

Buffy grabbed hold of the fur more tightly, in her left hand, and plucked the dagger out of her mouth with her right. "Doctor, stop trying to talk to it!" she screamed. "It can't hear you! It's deaf!"

And, from what she'd seen in hell, just a guard-dog. Non-sentient.

But the Doctor didn't hear Buffy.

Just took a step back, as the monster howled, and muttered to Seo, "All right. Deaf. Point to you on this one."

"Do you ever listen to me?" Seo hissed.

"I listened fine!" The Doctor replied. "I just wasn't prepared to take your assertion at face value."

Seo glared at him.

And the monster lunged for the Doctor.

Buffy stabbed her knife in the monster's back, and it reared back, once more. Spun around, flinging Buffy away so that she slammed against the side-wall of the alleyway, hissing with the pain.

It sniffed for her.

But couldn't sense her.

It began to turn back towards Seo — but Buffy pulled herself to her feet. And launched herself into another flip.

This time, she landed right smack on the creature's head.

And thrust her dagger into the area behind the left ear.

The instant she did so… a shot rang out, behind her. The Yixolpot slumped, in place, whining as it died. And Jack Harkness, revolver in hand, stepped forwards.

Looking right through Buffy, as if she weren't there.

"You two okay?" Jack asked the Doctor and Seo.

Buffy yanked her knife out of the Yixolpot's head. "You fired  _a gun_  in front of the Doctor?" She shook her head. "You're so gonna get it now, Jack!"

Sure enough, the Doctor was already on at Jack about how he'd been trying to figure out what was really going on, here — and killing that creature wouldn't help him find out any faster, would it?!

Buffy grinned, despite herself.

Looking on at the Doctor, standing there, just in front of her — and yet he couldn't even see or hear her.

"I missed you, you know," Buffy told him. "You've got no idea how much…!"

She paused.

Her eyes lingering on his face. Watching the way he held Seo's hand — as if he couldn't bear to lose her.

"Thanks," Buffy whispered. "For looking after her."

* * *

"…and if I could think of another way, I would have used it," Jack insisted. He tucked the gun away, before the Doctor could snatch it from him and throw it into a volcano. "Hey, after it went through you, Doctor, it would have gone for Seo. And you told me to protect her."

The Doctor was loathe to concede the point.

But Jack had pretty much hemmed him in.

"Father's right, though," Seo said. "You shouldn't have killed it. You should have just wounded it, so we could figure out what was going on."

Jack slumped. "You too, huh?"

"Next time, we should put a… tracker on it!" Seo proposed. "See where it goes when it's injured and trying to get help. Maybe we'll see who's behind all these killings."

"At the very least, we should figure out if it the creature was an animal, or some robot sniffer dog," the Doctor proposed. He let go of Seo's hand, and raced forwards, sonic at the ready. "If we could just…!"

He paused.

Frowned.

The others turned, to face him. And then stared, past him.

"It's gone," said Jack.

The Doctor tapped his sonic against his lips. "A vanished body," he muttered. "A creature I've never seen before. Everything's gone wrong in the future, and it all stems from this point." He spun around. Pointing at Jack. "And then… there's  _you_."

"Jack?" Seo looked in between the Doctor and Jack. Confused.

Jack looked confused, too, but was trying to hide it by being charming. "I'm in all the best stories," Jack said, with a wink.

The Doctor ignored him.

"I have these… theories," the Doctor continued. He gestured at his own head, with a flustered sort of shake of his hands. "Well, not theories, yet. More like… things. Things trying to be theories." He gave up the metaphor, frustrated. "How can a simple alien invasion on one planet destroy the whole future? What happens here that so fundamentally changes time? I have some ideas." He dropped the hand. "Problem is… Jack doesn't fit into any of them."

"Maybe the invasion leads to some scientist here developing a race of super-soldiers!" Seo tried. She pointed at Jack. "And they use something about him to make the soldiers immortal, and—!"

The Doctor saw the movement before Seo did, and grabbed her by the shirt-sleeve, yanking her out of the way. She only just barely missed being hit by the blast that intersected with the wall.

Jack spun around.

Seeing the figure darting away.

"I'm onto him!" Jack shouted, racing off into the distance.

"No, Jack, don't…!" the Doctor tried, but it was already too late. Jack was already gone. The Doctor stepped back, took Seo's hand in his. "Oh, Jack. It's pointless. There'll just be something else that shows up here, sooner or later."

* * *

Buffy was about to run after Jack, but stopped, when she heard the Doctor's words.

She spun back around.

"You've figured something out," Buffy realized. She charged back towards, him, analyzing his face. "Yeah — you've got this 'I'm-so-smart' look on, like you've just become Einstein or whatever."

"You've worked it out, too?" the Doctor prompted Seo.

Whatever the hell it was, Seo very clearly had.

Seo shifted, nervously. "Should we hide?"

"Hide?" the Doctor shook his head. "No. Hiding is for tortoises. Or snakes. Or… small furry creatures who burrow down into things." He grinned, flipping his sonic through the air and catching it. "Better idea! Let's hang around and see what happens next. Prove ourselves right or wrong."

Buffy didn't like that plan.

It put Seo in  _way_  too much danger!

But Seo — in typical Seo fashion — seemed to think it was brilliant.

"But are you sure they'll show up here?" Seo asked. "They didn't before you arrived. Jack and I went all over the place, and we never encountered any of these aliens!"

The Doctor's chirpy face fell.

"That's… a good point," he muttered. "And… very worrying."

They stopped talking, though, as a group of ghostly figures marched through the air just in front of them. Then, in a surge, faded into reality, as Cybermen.

"What?!" the Doctor cried.

Buffy was guessing that meant this proved his theory — whatever it was — wrong.

"You will be like us," the Cybermen declared. "You will be upgraded."

Other Cybermen marched into view, all pointing their guns straight at the Doctor and Seo.

"You will return the Cyberplanner," the Cybermen chanted, in unison.

The Doctor glanced about himself.

Then buzzed his sonic at the edge of the awning, stretched across the alleyway, above them.

The strings holding the canvas taught snapped, and the canvas flomped down on top of the Cybermen.

"Run!" the Doctor shouted, turning on his heels and racing off with Seo.

Buffy stayed behind, another minute longer. Okay, Cybermen. Cybermen. They were like… robots! Right? Buffy didn't know.

But she figured she had one shot at this.

She raced forwards, found the nearest fire hydrant.

And, moment the Cybermen came close enough, used her Slayer Strength to kick the top off.

Water shot through the air, splashing down on the Cybermen, making their circuits fizzle and pop.

"Upgrading," the Cybermen chanted, in unison.

And then they were off, again.

Still after the Doctor and Seo.

Buffy raced after them, trying to grab one back. It didn't see her, but used a metal arm to try to shove her aside — but she yanked at the arm, instead, bending down and using the momentum of the push as leverage to hoist him over her head and slam him against a wall.

The other Cybermen appeared not to have noticed.

Weird.

"Damn you, stupid robot things!" Buffy shouted, racing after them. "I may be a ghost, but I'm gonna haunt the hell out of you if you harm my daughter!"


	5. Chapter 5

"It doesn't make sense," the Doctor was saying, as they ran.

"I know!" Seo agreed. "I mean, why are they wasting time going after us, when there are all these people—" gesturing at the crowds around them "—that they could be converting into Cybermen?! Don't they have any sense of priorities at all?"

The Doctor shot Seo a sideways stare.

"What?" Seo asked.

The Doctor sighed, and got back to his running.

"What?!" Seo insisted.

The people around them began screaming with fear and running away, as the Cybermen ploughed through the dense crowds, murdering and destroying to get to the Doctor and Seo.

"There wasn't a Torchwood or a ghost shift, here," the Doctor went on, "and… if they arrived on Ariffildos specifically to retrieve you and get back their Cyberplanner — why didn't they say that until later? Why start with the upgrades and the…?"

Seo squeaked, as she dragged the Doctor to a halt.

Pointing at three more ghostly-looking figures, ahead of them.

"See?" the Doctor agreed. "That's just my point. The Cybermen have no reason to enter this reality using—!"

"Those aren't Cybermen!" Seo cried, dragging him off in the other direction, as the shadowy figures opened fire on them. "They're worse!"

The Doctor looked back at the three shadowy figures.

Then glanced over at Seo.

"They used the ghost shifts to hide!" Seo was trying to explain, as she stumbled onwards. "But they aren't ghosts! They're…!"

The three unearthly shapes then stepped forwards, turning into jellyfish blob things.

"Rutans?!" the Doctor said.

"What?" Seo shook her head. "No! They weren't Rutans."

The Rutans reached out a tentacle, but were blasted into goo by a troop of Sontarans, that had just appeared out of nowhere. Firing on anyone and anything nearby — including Cybermen and the innocent bystanders.

"Oh, now this is just getting silly!" the Doctor insisted, slowing to a stop.

Seo broke away from him, surging out to tackle a Sontaran that had been aiming for a little kid. The Sontaran fired too high, then turned around and started trying to thrash Seo away from him.

The Doctor dove in and scooped up the child, returning it to its mum.

Then tried to wade through the fighting, to drag Seo out.

* * *

 

Buffy swore, as she noticed the Doctor trying to wade into the fight and grab Seo out of there. She was distracted enough that she almost missed the green jellyfish thing stretching its tentacles out towards Seo, and had to shove a Sontaran in front of it pretty sharpish to save her daughter.

"Stay back, I've got this covered!" Buffy tried to shout at the Doctor, doing a flip-kick that toppled two Sontarans nearby. "All you're doing is giving me one more person I have to protect!"

The shooting from the still-advancing Cybermen turned the fighting back the other direction, the Sontarans now shooting at the Cybermen.

"We require the Cyberplanner," the Cybermen said. They fired, again. "Delete. Delete."

"No, you idiots!" Seo shouted, as the Doctor finally got in close enough to grab her away. "Don't kill them! Convert them! Release the Cybermats! Induce Cybercontrol! These people constitute tons of raw biological material just ready and waiting for you to… ow!"

The last exclamation being said in response to the Doctor bonking her on the head.

"Quick shock to the system to keep that Cyberplanner instinct in you at bay," the Doctor assured her. Then dragged her off. "Come on! We need to work out what, exactly, is going on here!"

Buffy leapt through the air, twisting and turning, bouncing off a few Sontaran heads on the way, so she landed right next to them, on the other side of the fighting.

"Cyberplanner instinct?!" Buffy shouted. She looked down at her daughter, with a disapproving glare. "What have you been doing to yourself since I've been gone?!"

"Thing is, these are monsters we all know!" the Doctor put in. "Save for that big blue-furred wolf, at the beginning." He glanced down at her. "We've been able to identify everything that's come for us! And I'll bet…"

The Doctor stopped running.

Bent down, turning Seo around to face him. Examining her, carefully. "You're hurt."

Seo pulled herself away. "Just scratches," she insisted. "I'll live."

"Exactly — scratches," the Doctor agreed. He grabbed up her arm, squinting at a scratch there. "You were fighting Sontarans. After that, I'd expect to see bruises, maybe a blast wound. But not scratches like these." He grabbed up his sonic, scanned the injury. Analyzed the result. "Residue of red brick. These were made by someone throwing you against a brick wall."

Seo frowned. "But… no one has thrown me against a brick wall."

Buffy, nearby, went very still. Her heart hammering in her chest, as she looked down at her own arm. And saw exactly the same injury.

And Buffy _had_ been thrown into a brick wall.

"Something's not adding up here," the Doctor said. He furrowed his brow, thinking very hard.

Then turned.

And… inexplicably… looked right at Buffy. Almost as if he could see her.

"There's something I'm missing, here," the Doctor said. "Something big. Something that explains this…"

Jack burst out of a nearby park, leaping over a bench and grabbing Seo by the upper-arm. "Weevils, two o'clock!" Jack shouted.

The Doctor raced after them. "Weevils? What's a weevil?"

Buffy followed, sprinting just behind the Doctor.

"Doctor, come on!" she shouted. "You looked right at me! You know I'm here! You have to know!"

The Doctor wasn't paying attention, though.

He was too absorbed in what Jack and Seo were telling him about weevils. And trying to make sense of all of this, in his mind, to come up with some clever theory.

"The murders only started when you two showed up," the Doctor said, looking between Jack and Seo. "And this chaos only arrived after _I_ showed up."

Jack and Seo nodded.

"And all these monsters are things we've faced time and time again," said the Doctor. "Almost like we _expected_ them."

"I don't…" Jack started.

The Doctor pointed at Jack. "You repeated what you told me after the Cyberman incident — that you'd protect her," he said. Pointed at himself. "That made me remember Cybermen." Pointed back the way they'd run. "Cybermen appeared."

"But…" Seo started.

"The moment Cybermen appeared," the Doctor went on, "I thought maybe they were here for their Cyberplanner. Suddenly, the Cybermen changed — started insisting on getting their Cyberplanner." He pointed back at Seo. "When I mentioned the ghost-shifts, you thought of something that happened to you, while on Earth, during those ghost-shifts. And those creatures emerged."

"Except they weren't really the same things!" Seo insisted. "They changed."

"Yes, but that's because I thought maybe these were shape-shifters, like Rutans," the Doctor replied. "Moment I thought it…"

"Rutans appeared," Seo realized.

"And then I saw the Rutans showing up from nowhere," Jack added, "and figured maybe this planet was a secret Sontaran base."

"So the Sontarans showed up!" Buffy cried. "I get it!"

"But the murders before this haven't been like that," Seo insisted. "Or not all."

"There was one body that looked like it'd been strangled by a snake," Jack explained, "but it left a—"

"Blue mark along the right cheek, and puncture wounds on the right palm?" the Doctor guessed.

Jack shot him a look.

"It's a fairytale monster, here on Ariffildos," the Doctor explained. "Conjured up out of the imaginations of the natives. It strikes once, then slithers away."

Buffy got it immediately.

"There's something on Ariffildos feeding on imaginations and stuff!" Buffy cried. "Making monsters come into existence. But you guys have seen way worse stuff than everyone else, so the moment you showed up, the whole thing went crazy!"

In the real world, the Doctor, Jack, and Seo were basically saying the same thing.

"Except," the Doctor continued, "that I don't understand where Jack fits into all of this. And I don't understand why Seo has injuries that…"

The Doctor stopped running, as he realized Seo wasn't keeping up with them.

He turned, and raced back towards her.

Buffy followed.

Seo was standing in the middle of the street, her eyes squeezed shut, concentrating very hard.

"Seo," the Doctor said, "what…?"

"What we think up comes true," Seo said. Her brow creased, deeper. "So if I think… hard enough… I can make Mom… reappear!"

Buffy felt her heart break.

She reached out to cradle the girl in her arms, but she drifted right through Seo. Ghost-like.

"I'm here," Buffy told her. "It's okay. I'm always here for you."

The Doctor put a sad hand on her arm. "Seo," he said, in a soft voice. "I'm sorry. She's gone."

Seo wouldn't listen to him.

"Whatever you conjured up, in her place," the Doctor continued, "it wouldn't be real. It wouldn't be her."

Buffy wasn't sure about that.

She wondered if maybe Seo — by thinking hard enough — could actually suck her through the Tartarus Gate and make her materialize on that planet right now. After all. Seo _was_ a Dimensional Key.

"Keep trying," Buffy begged Seo. "Come on. I know you can do it. Get me back, and I can protect you properly!"

"It wouldn't even be able to leave Ariffildos," the Doctor told Seo. "The phenomena is localized to this planet."

"Ignore him!" Buffy shouted. "Bring me back!"

But Seo slumped her shoulders, and gave up.

Now just looking miserable.

"Hey, it's not your fault, kid," Jack told Seo, patting her on the back. "Remember that."

"No, Buffy wasn't," the Doctor muttered, turning away.

Buffy could read the look on the Doctor's face. It was the one that said, 'it's not your fault because it's mine.'

She stomped her foot on the ground. "Snap out of it, you two!" she shouted. "I don't blame _either_ of you!" She spun to Seo. "You made a mistake. You got tricked. And yeah, maybe I should be angry about it, but — honestly — I'm just way too happy that Elizabeth didn't kill you the moment you got home to care." She spun to the Doctor. "And Doctor — whatever the hell the Time Lords were doing with that Crystallizer thing, that made me and Elizabeth go all switcheroo — I'm sure you tried to stop it! Maybe you even _did_ stop it! I dunno. But even if you didn't and someone else did then… whatever! Doesn't matter. At least…"

Buffy faltered.

Her eyes resting on Seo, a gentle smile on her lips.

"At least you protected her," Buffy said. "That makes up for everything."

The Doctor turned. And… inexplicably, once again… stared right at Buffy. Peering, as if… he could _almost_ see her.


	6. Chapter 6

"No, Buffy wasn't," the Doctor said, turning away. He cleared his throat, and then, very softly, added, "Besides, bringing her back this way wouldn't have worked. It's not feeding off our imaginations — it's feeding off our…" He drifted off. Then, in a voice barely above a whisper, "our fears."

He was hoping none of them had heard it.

The last thing he wanted was them hearing the truth and then conjuring up more imaginary fears for whatever else to feed on. Besides…

He spun around.

There was something… nagging at him, about all this. A niggling, naggling little something prickling at the back of his neck, every so often.

"What am I missing?" the Doctor asked no one in particular. "What am I missing?"

Something bad enough to cause the destruction of the future. Something that couldn't quite be seen — or maybe hidden in plain sight. An itch he couldn't quite scratch…

His mind began racing through possibilities before he fully realized what he was doing.

"Whoa!" Jack said.

The Doctor spun around, to find Jack and Seo facing the citizens of the world… all morphing into big, sucker-showing Zygons.

"No!" the Doctor decided, clamping down on the thought. "Definitely not…!"

But it was already too late.

As his own fear wore off, and the citizens morphed back into people… it had already sparked another reaction somewhere else. A gigantic, lumbering fish-thing came tearing down the pavement, reaching for the three of them.

Followed, right behind, by a group of mutant fish-people from the polluted lakes of Irgazontum.

"Note to self, Doctor," the Doctor muttered. "Stop thinking." Gestured at Jack and Seo. "Run!"

They spun around, and fled.

"If we're causing this," Jack said, "maybe we should just leave!"

The Doctor shook his head. "We're not  _causing_  it," he argued. "There was already a problem here — and one that we have to solve. Problem is, we're feeding off each other's thoughts in a psychic daisy chain, amplifying it!" He began fiddling around in his pockets, thinking fast. "There's got to be something I can create to tamper down the effect, in order to handle this properly without monsters appearing everywhere!"

Jack nodded, slowly.

Then, "Call me crazy, but… I'm not seeing how any of this is going to destroy the future."

"If we three think up something monstrous enough," the Doctor muttered, continuing to rummage through his pockets, "then I'm sure it could roam across the universe, destroying everything. I'm trying not to think about it."

"Yeah, but… whatever's causing these things to become real," Jack argued, "it's only located on this planet. You said if Seo conjured up Buffy, she wouldn't be able to leave — so none of these other things would be able to leave, either." He shrugged. "So… how's it going to destroy half the universe?"

The Doctor's frown deepened.

"You know, Captain," the Doctor said, "I hate it when you're right." He paused. "And I also hate it when Seo goes unusually quiet."

He looked around himself.

Then swore.

Because Seo was gone.

* * *

Buffy had noticed Seo slipping off, before Jack and the Doctor realized she was gone.

"I  _can_  think Mom back to life," Seo whispered, clenching her fists. "Maybe… just as a ghost! So I can tell her I'm sorry, and I didn't mean to, and… that I've tried to live up to her memory."

"You… tried to live up to my memory?" Buffy asked.

Aw.

She wanted so much to hug Seo right now. God, she wished Seo would pull her out of here. Just so she could hug her daughter, one more time, and tell her everything would be okay.

"…even if I failed," Seo muttered.

That was okay.

"As long as you tried," Buffy told her. "And you're still alive to talk about it." She tried to reach out for Seo, but could touch nothing. "Whatever you've done… I promise, I'll put it right for you. After I get out of here."

Seo kept concentrating.

And Buffy wondered… if the Doctor could almost see her… maybe Seo could, too. Maybe Seo could feel… even just the general gist of what Buffy was saying… if she really concentrated like this.

"If you can hear this," Buffy told her, "I'm sorry I didn't come sooner. I don't know what the Doctor was talking about with this… Cyberplanner thing… but I promise, I'm gonna come home and fix it. I'll…" She grimaced. "…I don't know… have Willow do some crimes-against-nature spell to make it better, again!"

Seo popped open her eyes.

Staring right at Buffy.

"Seo!" Buffy cried.

But Seo wasn't looking at her. She was looking past Buffy.

At the group of Cybermen that had just turned a corner, and were advancing towards Seo.

"Run," Seo whispered, "or stay?"

"Run!" Buffy shouted.

Seo turned. "Run," she decided. "Definitely run!"

Buffy raced after her. Listening as Seo tried to figure it out, muttering to herself.

"Cybermen," Seo said. "Why Cybermen?" She spun around a corner. "I'm not scared of them. It was the humans who hurt me, not the Cybermen." She shuddered. "So… why…?"

Buffy, meanwhile, was just trying to think of something she could do against the Cybermen advancing on her daughter.

She'd never faced Cybermen before!

"Remember what Dawn told you," Buffy urged herself. "She faced these things down. Just… remember what she told… you…"

Seo stopped running.

Froze, in utter terror.

"HALT!" came a screechy, metallic voice, up ahead. "HALT! OR YOU WILL BE EXTERMINATED!"

Buffy felt her blood run cold.

"No," Buffy breathed.

They were appearing, all around Seo. More and more of them, their eyestalks all the cold, blue glare that Buffy remembered from countless hell dimensions.

"No, Seo, anything but this!" Buffy shouted. "Think of something else!"

* * *

"Maybe it's something… we three thought up together," the Doctor said, racing off as he frantically tried to find Seo. "Maybe the three of us, all focusing as a single unit, on the thing we all — hands down — fear the most, will be enough to permanently recreate an army of…"

"…Daleks?" Jack prompted, pointing at the sky.

"Yes, good example!" the Doctor agreed. "If we all thought of something like Daleks, then…!"

Then, with a sinking dread, registered what he was seeing right where Jack was pointing. And discovered increasing numbers of Daleks, hovering over the planet Ariffildos.

"Ah," said the Doctor.

"EXTERMINATE!" said the Daleks, as they descended.

The sight of descending Daleks streaked across the sky sent a streak of complete terror through the Doctor. This was it. Had to be. The way the future died.

Then blinked.

And snapped himself out of it.

"Oh, no," the Doctor said. Concentrating, hard. "If you all came from my head, you can get right back in there." He pointed up at them. "Go away!"

* * *

Buffy was stuck.

No idea what to do, except to run beside Seo, as she tried to get away from the Daleks.

Nothing could beat Daleks.

Maybe Buffy could throw herself in front of the Dalek beam to save her daughter… but with Seo sharing the same injuries as Buffy…

"Funny hat!" Seo urged herself. "No. Then…um… wearing a dress! With makeup smeared all across their faces, and… and… flowers stuck in their gun-stalks!"

Buffy frowned.

What was Seo…?

"Come on, it worked in  _Harry Potter_!" Seo complained, glancing over her shoulder. "Be like the boggart! Change into something funny! Like… flying sushi!"

"EXTERMINATE!"

Seo yelped, as she darted out of the way of the shot.

And kept running.

"All right, not like  _Harry Potter_ ," Seo muttered. "Plan B. What beats Daleks?"

Just in front of her, an army of Cybermen appeared out of nowhere. Flocked by Draconians, Sontarans, Rutans, giant lizard people, and a group of tiger-women.

They leapt at the Daleks, as Seo scuttled for cover.

"Oh, you smart girl!" Buffy praised, darting for cover beside her. "You knew it was feeding off what you were thinking of, so you thought up monsters who could beat the Daleks."

Actually, Buffy wasn't sure any of these could beat the Daleks.

But at least this gave a little delay.

"Think, think!" Seo urged herself. "Has to be some way to permanently get rid of…"

Then all the color faded from her face.

As she looked up at the sky.

Buffy looked up, too.

The Daleks were disappearing, swept away.

Instead, a giant crack appeared, stretching across the blue sky.

"No," Seo breathed. Trembling. "It's happening again."

* * *

"What beats Daleks?" the Doctor said. Focusing all his efforts on the sky. "Well, since none of this is real past Ariffildos, anyways… let's feed you all my biggest fear."

The one thing he'd seen in that room, so long ago.

The one thing he knew was coming for him.

The sky split open in a gigantic crack — stretching across the horizon. A crack that resembled the one he'd seen in Amy's room, so long ago.

And one that sucked at the Daleks, sending them all, screaming, into its bright depths.

Gone.

"The one fear to trump my fear of you," the Doctor told the Daleks. "Acting as a psychic vacuum cleaner! Ha!"

Jack frowned. Pointed. "That's your biggest fear?"

"It's complicated," the Doctor muttered.

He really didn't want to go into it.

"Cracks in the universe, TARDISes exploding," the Doctor chattered on, "and then there's the future, but we won't need to get into all—"

"I mean," Jack interrupted, "are you sure it's  _your_  biggest fear?"

The Doctor hesitated.

Then turned back to Jack. "Well, considered Amy Pond isn't here," the Doctor said, "I don't see who else could…!"

The crack seemed to grow. Littler cracks spreading from it, across the entire sky — as if it were all made of glass. The ground shook — except it wasn't the ground, it was the whole universe shaking.

"What?" The Doctor cried. "But that's not possible!"

Cracks began to split open in the ground, around them. People screaming as they disappeared into nonexistence — like they'd never been born at all.

"None of this should be real past Ariffildos!" The Doctor stumbled forwards, waving his sonic around. "That's why I thought of it!" he cried. "It should have just mopped up the Daleks and gone away! But…" He checked the results on his sonic. Baffled. "But the universe is actually fracturing. It's actually dying! Why…?"

"Seo saw her own universe cracking and shattering around her, Doctor!" Jack shouted, over the mayhem. "She remembers it!" Pointed at the sky. "What did you think her reaction would be, seeing it crack apart, again?!"

The Doctor's face grew even graver. As it all made sense to him, all at once.

"Seo," he muttered. "A dimensional Key. The one force able to actually crack apart universes with her mind. And if my fear triggered…"

This was how the future died.

It all made sense.

Fast as he could, the Doctor spun on his heels and raced off into the distance.


	7. Chapter 7

 

"Do your trick!" Buffy pleaded. The universe was ending around her, just like what she remembered seeing in Seo's mind, so very long ago. And knew that panic had set in, inside of Seo's mind. Panic that wouldn't let her think of anything else. "Please! Think of… think of me! Think of home! Think of being safe!"

Seo cowered back, even further.

"Seo, just stop this, please!" Buffy said. "I can't lose you. Not yet!"

"Doctor, I found her!" came a voice just above.

Buffy looked up.

Found Jack pointing, the Doctor running forwards. Kneeling down by Seo, taking her by the shoulders.

"Seo," the Doctor said, very softly, "can you hear me? Seo. It's me."

Seo shuddered. "It's happening again."

"No, it's not," the Doctor assured her. "I'm here, now. It's all right. I can stop it."

Her eyes focused on him.

"Trust me," the Doctor said. "I'm the Doctor."

"You said you'd fix it last time," Seo whispered. "And then you died."

The Doctor winced. "That's right, other-me died in that alternate timeline — I forgot about that." Then, quickly, composed himself, and continued in the same calm, soothing voice. "This isn't like last time. It's not happening again. I can make it go away."

Seo stared at him.

Terrified.

Not sure whether to believe him.

"Trust me," the Doctor begged. "Let me save you. Please."

"Trust him!" Buffy agreed. "He'll fix this! I know he will."

Seo gave a hesitant nod.

And the shaking of the universe around them slowed. The cracks hesitating in the sky, beginning to retreat.

"See?" The Doctor said. "Just like that."

Seo looked around herself.

As the universe stopped shaking. The ground knitted back together. All the cracks closing and sealing up. And the universe returning back to normal.

The Doctor gave a breath of relief.

"Thank you," Buffy said. "Whatever you did… thank you, thank you, thank you!"

"What did you do?" Jack asked.

"Quelled her panic," the Doctor replied. He helped Seo up to her feet. "Breathe. Slowly. Got that? Don't worry about a thing — I'm here. I won't let any harm come to you."

Seo breathed, heavily.

Trying to calm herself.

"That's it," the Doctor urged. "Good girl. Just keep calm, and everything will be fine."

"But… the fear-goblins," Seo insisted. "They're still making us think up monsters! They're…!"

"…surprisingly heavy on Cybermen," the Doctor said. "Don't you think?"

Seo frowned.

"Now, best you two know the truth," the Doctor said to them, his voice still as low and soothing as he could make it. "There's something in the air around here, conjuring up fears. That's true. But it was completely inert…"

"Until the first murder," Jack said.

"Until you two showed up," the Doctor corrected. "That's when my friend Bob said the murders started. Breathe!" He spun back to Seo. "In! Out! Calm!"

"It's not helping, when you keep telling me, in a stressed-out voice, to remain calm," Seo hissed.

"Ah." The Doctor stepped back, beaming. "Fair enough. You've already guessed."

Seo closed her eyes. Struggling to keep herself calm. "It's me," she confirmed. "My fault."

Jack looked between the two of them. "What…?"

"Well, not consciously your fault," the Doctor said. Then, with a glance at Jack, he pointed towards Seo. "Whatever this thing is, feeding off our fears," he said, "she's the one making those fears real enough to kill people."

"Everyone's so scared of things happening to me," Seo continued, breathing slowly, "that you made me the focus. Your fears all go through me — and I make them real." She paused. "Or I make them Cybermen."

Buffy stepped away from them.

A sudden chill running over her.

"Oh, no," Buffy said. "That's… not…"

"When the Sontarans showed up," the Doctor said to Jack, "there were… other creatures, in the middle of the fight. Demons that I last faced down with her mum. Perhaps I subconsciously thought of them, because the two look so similar. Perhaps I was imagining…"

The Doctor trailed off.

"Not you," Buffy said. "It was  _me_! Those monsters came from  _me_!"

"Fear of a parent for a child," Jack offered. "Worst fear of them all."

"Yes, well, technically, she isn't my…" the Doctor stopped, at the glare from Seo. Cleared his throat. "Let's… leave that for later, shall we? Some time when we're all… calm."

Buffy spun around.

"Red-horned demon things!" she shouted. "Get me out of here!"

No answer.

"I changed my mind!" Buffy screamed. "I don't wanna be here, anymore! Whatever you're using me to do, it's over! Just stop this!"

Still no answer.

"Get me out!" Buffy shrieked. "Get me out right…!"

* * *

"…now!"

Buffy looked around herself.

Realizing… she was nowhere. The absence of light and dark. The absence of up or down. It was… dizzy and terrifying and… weird.

"We don't have long."

Buffy spun around.

A woman was standing nearby. She had on a dazzling, Arabian-looking gown, with soft brown hair and sparkling eyes.

"Hell goddess?" Buffy asked. "Demon? Or… what?"

"There's no time!" the woman insisted. "My name is Terazina. And I'm here to repay a kindness."

A wave of something flashed through the nothingness.

And Terazina cringed, at it. As if this just proved how little time she really had.

"Look, whatever you're doing is great, but… I really just want to get out of here," Buffy admitted. "I mean, the sooner I get out of this simulation thingy, the sooner my daughter will stop being in—"

"She's in more danger than you could possibly imagine," Terazina interrupted. "They all are." Held out her hand. "Now give me the letter."

Buffy blinked.

Then shuddered back, suddenly on her guard, again. "Those letters are for  _Seo_ ," she insisted. "I'm not…!"

"Buffy Summers," Terazina said, with a sigh, "you can't win this without me. It's already too late. The odds have been stacked against you."

"Too late?!" Buffy cried. "What do you mean, it's too late? I can still—!"

"No, you can't!" said Terazina. "Don't you see? That's why I was so sure that Seo would never send me back. Because I knew what would happen. So did they. Everything has been predicted."

Buffy blinked.

"They knew Seo and Jack would be on Ariffildos," Terazina continued. "They knew the Doctor would be clever and see past the artificial timeline, to work it all out. They knew who'd do the research, they knew who'd be impulsive. They knew of the catastrophe, and they knew of the Havchornom's plans. Everything was fixed. Everything has been assured."

Just like the Crystallizer.

Fighting fate.

"So we're screwed," said Buffy, "no matter what."

"But Seo sending me home…" Terazina continued. She shook her head. "No one ever expected that. One single act of kindness."

"…that changes the course of history," Buffy muttered, remembering what Sineya had told her. "I get it."

Terazina nodded, satisfied. "Good," she said. She held out her hand, again. "Now. The letter."

"Which…?"

"You know which one," Terazina replied. "The setting of your worst nightmare."

Buffy reached for it, in the inside lining of her jacket.

Then… shuddered.

"I'll… give you any other letter," Buffy pleaded. "But not that one. Please! I… I didn't even finish writing it!"

"It has to be that one," Terazina replied. "Only that letter will be guaranteed to fall into the right hands. And only in the right hands may our actions save a life."

The landscape around them shuddered, with another stream of something, blowing through the nothing.

"Time is short!" Terazina urged. "Give it!"

Buffy handed it over.

And the moment she did, all the nothing — and Terazina, too — blew away, leaving Buffy right back where she started.

In the middle of a simulation that she, herself, was influencing. As a bunch of demon things tried to use her own fear to destroy her child.

"And the only thing out there that might tell any of you what's really going on," Buffy said, looking out at them all, "is a letter smudged with tears, that I didn't even manage to finish."

She shuddered.

Then forced herself to remain calm.

"No, this will be fine," Buffy said. She turned to the Doctor. "You've almost seen me. You know something else is going on. She's going to give the letter to you, and then… you'll know exactly how to fix this. I'm positive."


	8. Chapter 8

"But that's impossible!" one of the Havchornom shouted at the projection in the middle of the table. The Doctor was strolling alongside Jack and Seo, the three of them talking, no monsters in sight. "He can't have quelled the panic! He can't have managed to stop the monsters!"

"They say… one should never underestimate the Doctor," the second Havchornom muttered. "If he's found a way to make the girl stop accessing the Gate—"

"The Doctor is a Time Lord," the first Havchornom hissed. "The Time Lords never knew about the Tartarus Gate. It's the only one they didn't know about!" It huffed. "Besides. You know the future. He doesn't cut the link."

From across the room, staring into a crystal ball, the third Havchornom froze. "Uh… Clim? Gren? I think… I've found our problem."

The others raced over to the crystal ball.

"Did the Time Lord cut our link?" said Clim.

Gren squinted into the crystal ball. "No, it's not the Doctor… it's something else," Gren said. "Something we can't quite see. As if someone's trying to change the catastrophe itself."

"But that's…!" Clim insisted.

"Impossible, yes, I know," Gren replied. "But that's what it seems to be. The catastrophe is in question. And if there's no catastrophe—"

"Then the fear and panic we've been feeding off of goes away," Clim agreed. "And so do all the monsters." He pointed into the crystal ball. "Kip, what is that?"

Kip brought it forwards into the crystal ball.

The image was flickery, unable to stabilize or make any visual sense. The time factor within it was garbled enough to be nearly indecipherable.

"We can't see it," said Kip. "Can't grasp it. And so, have no hope of changing it. Whatever just happened to Buffy Summers, seconds ago, when she was removed from reality — it's set in stone."

They peered into the crystal ball, even harder. Trying to make out something that could explain what had just happened. Or what long term consequences it might have.

Someone had taken a letter. The letter had been bestowed with some mystical property. It had been tossed out the Gate, using forces beyond their understanding. But everything still remained jumbled and confusing.

Except for one phrase.

_"One single act of kindness…"_

The Havchornom all looked at one another. And realized…

"What's happened to Summers only has the  _potential_  to alter the catastrophe!" said Clim. "It hasn't actually altered anything, yet!" He raced back to the table. And fiddled with something. "That initial moment of panic and defeat and horror still exists. I can  _taste_  it. Latch onto that… and we can send Ariffildos back into a frenzy!"

"We will feed," said Gren.

"We will feed," said Kip.

* * *

"Chin up, easy does it!" the Doctor said, marching ahead of Seo and Jack, a big grin on his face. He plucked some party hats out of his pockets, and set them all on one another's heads. "See? Happy thoughts! Very happy!"

Seo was clearly trying hard to focus on actually  _being_  calm.

Rather than whatever the Doctor was saying to her.

"Chocolate cake," Seo whispered to herself. "A warm, sunny day, with friends. Staying up late with Alison and gossiping about boys. That moment when everyone says, 'Good job, Seo', and tells me I'm brilliant — which I am. Having Dave touch me. Converting whole worlds into Cybermen…"

She paused.

Frowned.

"Scratch that last one," she decided. "I'll stick with Dave."

"I'll stick with him, too," Jack chimed in. "A bit of a prickly personality, but you can't fault the looks!"

Seo opened one eye enough to elbow Jack in the side.

"So where to now, Doctor?" Jack asked. "Find whoever's doing this, cancel it out, and fix the universe?"

"Something like that, yes!" the Doctor agreed. "Long as we keep positive. Calm. And upbeat! Good thoughts! Then we just find whatever's in the air, here. Get rid of it. And…"

In unison, the entire planet of Ariffildos shuddered.

Jack gripped his military greatcoat tighter — like he'd suddenly been gripped by a chill. "Did you feel…?"

The Doctor did.

So did Seo.

"Ah," the Doctor said, staring out into nothing. "I… didn't think of that."

"What?" said Seo.

"Whoever it is must be tapping into a great source of fear, to make these projections real," the Doctor said. "I assumed it was our worry over Seo. But… I'm starting to think…"

Another wave of terror swept across the planet.

"…it's being sent from the future," the Doctor said. "When it gets destroyed."

The wave crashed over them, again.

And again.

Until they couldn't hold out anymore…

And the monsters returned.

* * *

"Calm, Buffy," Buffy was telling herself, sitting on the floor of the chamber. "Calm. Relaxed. Deep breaths."

The landscape seemed to have realized she wasn't keeping up.

And was drifting alongside the Doctor, Jack, and Seo, anyways.

But as long as Buffy decided she wasn't going to interact with the world around her… it seemed to be perfectly content leaving her alone.

Around them, the monsters were re-emerging. Slitheen, this time. All lunging at the Doctor, Jack, and Seo. The three trying to sprint for it, Seo struggling to keep herself under control.

Buffy tried to drown it out.

"It's not real," Buffy insisted, out loud. "You're just trying to panic me. I know Seo's brilliant enough to get out of this on her own. She doesn't need me."

Then came the horrible black creatures that made Jack shake in his boots, and which Seo recognized as "the Yugzode."

"It's okay, Jack!" Seo reassured him. "They're not actually that scary. I'll protect you."

The Yugzode slashed at Seo, and she cried out.

Buffy gritting her teeth, forcing herself to remain calm.

That Terazina person said Buffy's letter would save Seo. Even if it was too smudged to tell it was Buffy's handwriting. Even if there was no signature at the bottom and the contents might make the Doctor and Seo think Buffy had died in hell, calling out for her child…

"No," Buffy said, closing her eyes and trying to drown out the noises surrounding her. "She'll give it to Seo. Seo will know it's me. She was trying to bring me back!"

The sound of gunshots.

"Get down!" Jack shouted.

Buffy forced herself not to look. To remain calm. Easy does it.

"Wait, I  _know_  that sniper!" Seo cried.

" _You_  know that sniper?" said Jack.

"Yes, she's that Johnson woman!" Seo said. "She tried to kill me, during that Year that Never Was, while you were on the Valiant with the—"

"Oh, no!" the Doctor interrupted. "Nobody think about the Master!"

Buffy's eyes popped open.

Just in time to see a swarm of Toclafane descend from the sky, along with a bearded, laughing man holding a small wand with a ball at the end.

"Too late!" said the Doctor. "Run!"

The Toclafane descended.

And Buffy watched as, all around her, the metal balls grew spikes and began slaughtering and shooting people down. Seo screamed, Jack yelped, the Doctor was chattering — all three driven further and further away from one another.

Buffy looked around herself.

"Help!" Seo cried.

Then Buffy jumped to her feet. "Screw it!" she decided. Racing off. "Hang on, Seo! I'm coming!"

She chased after Seo, leaving the Doctor and Jack on their own, helping to punch and fight and kick the monsters away as best she could.

And desperately trying not to think.

"I believe in Seo," Buffy said. Punching a lizard thing in the gut. "I'm not afraid. There's no one who can show up, now, that'd make me panic more than Daleks…"

"Well," said the southern accent that cut through Buffy's thoughts. "If it ain't the filthy whore herself."

Buffy's blood ran cold.

The other monsters all parted and then ran, as the man emerged — seemingly from nowhere. Looking just like he had the night he'd gouged out Xander's eyes.

"I take it back," Buffy breathed. "Way scarier than Daleks."

Seo tilted her head to one side. "I think I object to that."

He stalked towards her.

Buffy raced between him and Seo. But with no Scythe around… how would she ever stop him? He'd kill Seo with relish first chance he got.

"More importantly," Seo said, eyes scanning him up and down, "who are you? Are you one of Jack's fears? Or Father's? Because I'm pretty sure I've never met you."

"Come on, Seo," Buffy pleaded. "Work it out. He's a bad guy! You've gotta run!"

"Oh, but I've seen your wicked ways," Caleb continued. "All you little girlies, with your sinful, wicked whiles. And I met your mommy, little whore. She was the queen of the filth, she was — ain't no mistake about that. A veritable—"

Seo growled, nearly shoving Buffy to the ground as she leapt at him, eyes blazing. "Don't you dare talk about my Mom like…!"

He caught her off-guard, spun her around and slammed her hard against the pavement before she could do anything.

Buffy tried to block the tackle, but the advance had happened too quickly. She tried to race out to stop it, but a Halsom demon jumped into her path, knocking her off-course.

She could only stare, as Caleb grabbed her daughter up by the throat…

Panic overtaking Buffy, as she knew what would happen, next. Knew that he was going to snap her neck, right there and then, like Buffy had seen him do to all those others, and (stop thinking, you're making it happen, Buffy, your panic is making this happen!) and there was nothing she could do she couldn't even move she couldn't…

"Time to watch a whore die," said Caleb.

Which was when the leftmost wall of the simulation room was blasted apart.

The blast making the simulation flicker, then die out into blank white walls, around Buffy. No more access to Caleb or Seo or the outside universe.

Buffy turned. And stared at the tall blond girl who'd just stepped inside the chamber, and was now lowering her gun from her shoulder, eyes still fixed on Buffy.

"I don't believe it," said Jenny, gun in hand. "You actually  _are_  alive!"

"But… but… what?!" Buffy jumped to her feet. "How are you here? How'd you figure out I was still alive? How'd you even…?"

Jenny gave a small grin. And waved a small bit of folded paper.

"I got your letter," she replied.


	9. Chapter 9

The Doctor frantically tried to dart and dodge out of the way of monsters, while simultaneously cobbling together equipment. He tore through a market stall, grabbing an electronic whatsit from someone's hand as he did.

"Just borrowing!" the Doctor called back, jumping over the table. He slammed it into his device, glanced over his shoulder. "I'd run, if I were you!"

Then zipped off, in the other direction.

"Inverse vector generator," the Doctor muttered, eyes skimming over the machinery as the Toclafane fired again — and barely missed. He skirted to the right, into an alleyway. "Crystalline field dampeners. What am I missing? What am I…? Ha!"

Yanked out his sonic screwdriver, and gave the whole thing a buzz.

"Trusty buzz of the sonic!" the Doctor cried, as the gizmo in his hands suddenly whirred into life. He smiled, then turned around.

Pointing it at the swarms of Toclafane in the sky.

"And… off!" the Doctor said, slamming his hand down on the button.

In the blink of an eye, the Toclafane vanished.

Leaving the Doctor grinning, ear-to-ear.

"An intriguing development," said the Master, stepping into view. Tissue compression eliminator aimed at the Doctor. "But ultimately futile to my overall plans. Goodbye, Doctor."

"Ha! The Master, complete with his ego!" the Doctor beamed. "You think you're real, don't you? More than that — you think all these monsters and everything on Ariffildos is your plan!"

The Master hesitated. Then overcame his hesitation. "You cannot hope to distract me with your ridiculous—"

"Bet it stings, doesn't it?" the Doctor continued, brushing his fringe out of his eyes. "Finding out you're just a figment of my imagination." He began walking towards the Master, calmly. "I could get rid of you with just a thought. Know that?"

"Lies," the Master insisted.

"No, really, it's true!" the Doctor gestured up at the sky. "Look what I did to your Toclafane! Could do it just as easily to you… if I wanted to, of course." He stopped, just in front of the Master. "Or… you could prolong your own existence. By helping me."

The Master responded by thrusting the Tissue Compression Eliminator in the Doctor's face.

"Oh, very well," the Doctor muttered. "Worth a shot." Took out his gizmo, began to alter the settings.

The Master cried out, stumbling backwards, as he began to fade. "No, this… this cannot be!"

The Doctor stopped his fiddling.

Looked up at the Master.

"You ready to give me a hand?" the Doctor asked.

The Master went very quiet. Then, in a dull voice, "What is it you want?"

The Doctor's beam grew. "To make little things we can't see in the air big enough to get rid of them?" As he held out his hand. "I'll be needing your Tissue Compression Eliminator, please."

* * *

"I was half-convinced that someone was setting me up for trap the whole time," Jenny said, as she and Buffy raced off and found themselves in a maze of white walls. Jenny paused by one of them, hunting for a marking she'd made, earlier. Found it. And continued. "Something's happened out there, you know. The future's been destroyed. All these planets and people that should be around — suddenly gone!"

"The catastrophe," Buffy said, recalling what she'd heard the Havchornom say. She blinked. Then frowned at Jenny. "But you weren't on Ariffildos."

Jenny glanced back over her shoulder at Buffy. "I wasn't about to jump into a situation like that without gathering a little intel, first. Like I said. Could be a trap." She shrugged, returning her eyes to the front and adjusting her huge gun. "Thing is, when I went to do the research, I found your letter. Or… I guess… your letter found me."

She slowed a little.

Her face in animated curiosity.

"What do you mean, found  _you_?" Buffy said. "Wouldn't it find  _Seo_?"

"I don't think she was full-blooded enough for that to work," Jenny replied. "It was either me or Dad… and I guess it found me, first." She stopped, completely. Then spun back around to face Buffy. "Was the sky really a burnt orange? With snow-capped mountains in the distance and red grass?"

Buffy bit her lower lip. It was the place in her letter. Jenny wanted to know about  _that_.

Buffy pushed past her. "I don't want to talk about it."

"But you have to!" Jenny insisted. Caught her arm. "It shouldn't even  _exist_ , and… and… and you stumbled across it! Is anyone still alive, there? What was it like? Did you get to see the glass dome, or was that destroyed?"

Buffy gritted her teeth.

Wasn't gonna think about it.

Wasn't gonna ever talk about it, again.

"At least just… tell me where it is!" Jenny pleaded. "And how you got there. And how we can get them back! I mean, whatever's destroyed the future…  _they_  can fix it. It's what all the stories say!"

"I don't care about stories or whatever!" Buffy shouted. "That place was torn apart by Daleks. I saw  _no one_  alive. At all. The Doorway's gone, my hell-hopping ring is gone, and — whatever magical hell thing you think you can pull out of that hell dimension and use — it's gone, too."

Jenny went very quiet.

"Besides, I don't even know when I showed up there," Buffy muttered, turning away. "The ring was unstable and all time-jumpy, and… and…"

That same image of Seo dead in the midst of the red soil and burnt sky flickered into her mind. She remembered when Sineya had appeared there and spoken in riddles. Was that Seo's future? Buffy could feel the panic flowing through her. And tried to force it all away.

"Let's just get out of here," Buffy insisted. "Get through the Gate, go to Ariffildos, and save my daughter. That's all I want to do."

Jenny remained quiet.

Then, very softly, "We can't go to Ariffildos."

Buffy blinked. Then, her anger blazing, blew up at Jenny. "What do you mean, can't go to Ariffildos?! The Doctor's in danger! Jack's in danger! My daughter could  _die_ , and you think…?!"

"There's an energy trail leading from Ariffildos to Cerebus Iera," Jenny interrupted. "It's how I found the Gate, and found you. I figured the planet's name was a pretty good tip-off that I'd found the Gate to Hell, and could find you floating around somewhere inside." She shook her head, with a sigh. Looking down at the letter. "You  _really_  don't know how you got there? Or when? Or where?"

"Don't you think, if I could have controlled where and when I went, I'd have saved that hell dimension, too?!" Buffy snapped. "No, I don't have any idea. And, yeah, those guys were all human and I let them down, I let them die — but that Terazina person said Seo was in trouble, and I'm not letting  _her_  die. I can't…!"

"You really have no idea where you were, huh?" Jenny muttered, so quietly that Buffy didn't hear. Tucked the letter away into her pocket, then slung her huge gun over her shoulder. "Human. Ha."

Buffy's face was bent into thought, however.

As her mind raced, furiously, to try to figure out what the hell was going on.

"An energy trace leading  _here_ ," said Buffy. "And if the Doctor was right — those Havisham demon things were using me to create those monsters. Feeding off my fear for Seo." She brushed some hair back over her ear, as everything clicked together in her mind. "But that'd mean a massive energy rush going  _out_ , not coming  _in_  — like you said. So… they're…"

"Feeding off the fear and panic generated on Ariffildos," Jenny agreed. "I know."

Buffy looked up at her. "You know?!"

"Well," Jenny shrugged, turning to head off in the direction of her black marks. "I guessed. Now, are you coming to help me stop those demons, or are you staying here?"

Buffy blinked. Digesting all this.

Then raced forwards, after Jenny, fast as she could.

"Note to self," Buffy decided. "Never try to outsmart the Doctor's kids. They'll always have figured it out before you."

* * *

Seo knew she had one chance, with this Caleb guy.

"You… will…" she choked out.

"Lil' harpie like you got somethin' to say?" Caleb asked.

"You… will… be…" Seo wheezed. Struggling.

Caleb leaned in. "What'll I be, lil' girly?"

Seo stared straight into her eyes, tapping into every bit of Cyberplanner she had left in her. "Up…graded…"

It worked.

Blink of an eye, and the figure of Caleb rippled and changed. Silver tinting his skin, spreading across him and growing until he had morphed completely into a Cyberman.

The grip on her throat loosened — just a little.

"Upgrade complete," said the Cyberman. It paused. Then, letting her go, "You contain the Cyberplanner."

Seo fell to the ground, stumbling to catch herself and wheezing to regain her breath. "Yes," she gasped. "In my head."

Not exactly the same way they'd left their precious Cyberplanner, but no need to tell them that.

"We must extract the Cyberplanner," said the Cyberman, pointing his gun at her. "You will submit for extraction, or you will be del—"

The Cyberman never finished.

As he popped out of existence.

"To be honest, I'm not sure how I feel about you turning your adversaries into Cybermen," the Doctor said, racing out with a boxy-looking gizmo in his hand. He quickly used it to clear away any other monsters lurking nearby. "You sure you have that Cyberplanner completely under control, up there?"

Seo's eyes lit up.

As she raced forwards, and swept the Doctor into a great big hug.

"I wouldn't ever turn you into a Cyberman," Seo muttered. "I like you huggable."

She froze, as she saw the black-clothed figure lurking just behind the Doctor. Jumped away, quickly, her eyes wide, pointing.

"It's the Master!" Seo shouted. "He's—!"

"Friendly," the Doctor said. Frowned, realizing that was a lie. Then amended, "Helping us because he's scared for his life."

The Master gave a bitter laugh.

Little pointed beard twitching with the action.

"He destroyed the Irkoli Empire," said Seo, her face growing dark. "Plunged that galaxy into war! To say nothing of what he did to Earth and the human race, during that Year!"

The Master stepped forwards, calmly. "You don't forgive me," he said, "but you'd forgive a multi-dimensional entity who tried to destroy a universe simply to get home?"

Seo faltered. "That's… different."

The Doctor gave an irritated sigh. Then pointed at the Master, and said, "You only know that because you're a composite of all our minds." Spun back around, put an arm around Seo's shoulders. "He might be evil, but he's also brilliant. And, besides — if he gives us any trouble, I'll let you turn him into a Cyberman. How's that?"

Seo glared at him, a little more.

Then, finally, nodded.

"Splendid!" the Doctor decided. "Time to go rescue Jack from whatever trouble he's found for himself. Finish up with that TCE. And save the future!"

He raced off.

Then stopped.

Realizing the others weren't with him.

"Jack…" Seo muttered. Her glare at the Master turned into a ponderous stare. "Now there's something that doesn't make sense."

The Doctor swung around. "Who, Jack? Ah, well. I've been saying that from the get-go."

"No, not Jack —  _him_ ," said Seo, pointing at the Master. "It's the wrong Master."

The Doctor suddenly frowned.

Staring at the Master, intently. At his black clothes and dark hair and little pointy beard.

"The Master after he visited Traken, whom  _you_  saw in the Irkoli Galaxy," the Doctor muttered. "But not the Master that Jack knew on the Valiant." He tapped his chin. "And if it had come from all three of our minds…"

"…then he should have been the Master on the Valiant, yes!" Seo agreed.

The Doctor's frown deepened.

"And all Jack's greatest fears who've shown up," Seo continued, "are things  _I've_  met, too. But since he's been traveling through the universe a lot longer than me… shouldn't he have fears that I haven't met, yet?"

The Doctor thought a long moment.

"Well! Better go find him, then," the Doctor decided. Turned, and raced off. "Come along, you two! Don't dawdle!"


	10. Chapter 10

"You know," said Jack, gasping heavily as John Hart kissed him, "after all I've seen and done, I can't believe  _you're_  my worst fear."

"Worst fear? I'm touched," said John Hart. He ruffled Jack's hair. "Knew you went in for the kinks, but I never thought it scared you."

Jack's eyes went to the sky. "There's stuff out there I've faced that  _still_  gives me nightmares," he said. "The Velzindrious Echop. The Iploti on that Corona planet. The 456." He shook his head, eyes turning back to Hart. "Not you. You're just a pain in the ass."

"You bet I am," said Hart, grabbing Jack's rear.

Jack shoved him away. "Makes me almost think you're  _real_ ," he said, "and on one of your 'side-trips'. Those Ecwousi sisters caught up to you, yet? They were supposed to have pretty comprehensive psychic powers."

"Maybe what you really fear," came a voice to Jack's right, "is someone from your past showing up in your present."

Jack spun around.

Then groaned.

"Suzie Costello," Jack said. "I wasn't afraid of you, either."

Suzie raised up the resurrection gauntlet, on her hand. "Scared of your past showing up and biting you in the ass, though, huh? Not like you used to be squeaky clean."

"That's because every time my past shows up, things go to hell." Jack shook his head, and pushed past them. "Now get away and leave me alone."

"Past always catches up to you in the end!" Hart shouted after him.

Jack blocked them out.

As he stormed away from them.

"How about the Uciko of Malterna?" Jack muttered, hands clenched into fists. "The Dreaded Barbarachi? I got trauma enough to last me lifetimes — and this fear-goblin can't even get inside my head enough to see…?!"

"Good point, Captain!" came the Doctor's cheery voice. "Top marks! Gold star!"

Jack jerked his head up, to find the Doctor, Seo, and… someone in black clothes with a pointy beard and malicious smile… all headed towards him.

The Master, the Doctor had said.

Must be another incarnation.

"See, I can understand how the events here would create that destroyed future," the Doctor explained. "Simple! My greatest fear, turning into Seo's greatest fear. Feed them together and — if I hadn't been quite so brilliant and figured it out quickly as I did — nearly every planet after this point would have been turned to a burnt-out husk."

The Master scoffed at the Doctor's assertion of his own brilliance.

But remained silent.

"But there's something very wrong with Jack, and I can't help but think it's related," the Doctor concluded. He handed his gizmo to Seo. Then spun back, and grabbed a black tube out of the Master's hands. "First things first, though. Now that we've modified the Tissue Compression Eliminator…"

He tossed the TCE to Seo, who caught it. Quickly stuck it in the Doctor's device, then pressed the button.

Jack started backwards, as he noticed something twitching in the air.

Something that had once been microscopic, now growing, ever larger and larger, into floating green globs.

Writhing, floating green globs.

"Ha!" the Doctor cried, clapping his hands. "Big enough to see you, now!"

Seo made a face. "We've been breathing in  _these_  things, ever since we got here?"

"Yep," said the Doctor. He turned to the Master. "And I'm guessing you recognize them."

"Fascinating," the Master said, studying the green globs, intently. "Havchornom Spores."

"Exactly what I was thinking," the Doctor concurred.

"Quite impossible," the Master muttered. "And yet—"

"You're forgetting where we are," the Doctor countered. "And what you did, a million years ago."

The Master paused. "Ah. I see."

Jack and Seo looked at one another.

Neither any the wiser.

"Huggy Chummy Spores?" Seo asked. "What are…?"

"The  _Havchornom_ ," the Master cut in, impatiently, "are a race from the Dark Times. They allied themselves with the Great Vampires, and were completely and utterly wiped out by the Time Lords."

"Or so the story goes," the Doctor amended. He bounced on his toes. "Of course, since one of the Great Vampires managed to flee to another universe… it's entirely likely that some of the Havchornom escaped, too." He shook his head. "Nasty bunch."

"They escaped out of the universe, and now they're trying to get back in?" Jack guessed. "Is there some kind of rift or gateway, here, that could…?"

"The planet Ariffildos had another name, once," the Doctor cut in, gesturing around them. His eyes fell on Seo. "Bytopin."

Seo's eyes went wide. "Bytopin! But that's in the Irkoli—!" She looked between the Doctor and the Master. Then pointed at the Master. " _He_  let the Havchornom back in!"

"Almost," the Doctor said. He grinned. "I have a feeling that when the Master opened that dimensional fissure, they did try to invade. But  _you_ , Seo, sucked them right back out of the universe, again! Brilliant trick you did with the black hole."

Seo didn't seem placated.

Her eyes still fixed and glaring at the Master.

"But even if the Havchornom didn't come through, their spores did," Jack guessed. "They wound up concentrated on the planet Ariffildos — and Seo activated them just by showing up here."

The Doctor steepled his fingers in front of his face, thinking it through. "Yes, I suppose…" Then, with a glance at Jack, "You didn't suggest she come here, did you?"

"No," Jack replied.

"Terazina told us where and when to go," Seo added. "Except then she warned me not to come. But I didn't listen."

"Tera—? No, never mind. Topic for a later time." The Doctor brushed his fringe out of his eyes. "Most important now is the Havchornom. If they've infected the Irkoli galaxy with their spores, they could do untold damage!"

"But only if I show up," Seo said. "I'm what's making these illusions real!"

The Doctor shook his head. "Believe it or not, monsters appearing out of thin air is the least of our problems with the Havchornom, Seo."

Jack nodded, slowly. "I'm guessing this is where I come in, then. And the explanation as to why these spores aren't able to get to my fears, properly." Prepared himself for the worst. "So. Out with it. What else do these Havchornom do?"

"The Havchornom don't just manipulate thoughts," said the Doctor. "They manipulate time. In particular, they're very good at manipulating the recent past."

"And Jack's…!" Seo realized.

"…a fixed point, yes," the Doctor agreed, giving her a proud pat on the back. "Which is why he isn't affected in the same way we are."

"Manipulate time… how?" Jack asked. "If they can't mess with fixed points… we're okay. Right?"

The Doctor sighed. "Trouble is… they use their manipulation of the recent past as a weapon. Whatever plan we come up with against them now, for instance, they'll know about it. And already have countered it."

"Correct, Doctor," said the Master, a stazer suddenly in his hand.

He fired straight at the Doctor.

* * *

"Good one, Climp," said one of the Havchornom, watching it all play out in the center of the table. "A little predictable — the Master trying to kill the Doctor. But the classics are always the best."

"The Doctor has such a fascinating mind," said another, twisting around his head to peer more closely at the image. "Always twisting and turning the possibilities. And so far from seeing the whole truth!"

They were interrupted by the sound of the wall being vaporized, beside them.

And a tall blond girl with a gun stepping forwards, leveling it straight at the three demons. "One chance. Tell me what's going on and how to stop it. Or you get very dead very fast."

The three Havchornom seemed surprised.

But remained perfectly calm.

"I'm not messing about," Jenny warned. "You've got until three." Charged up the gun. "One… two…"

Buffy put a hand on Jenny's arm.

"They're… not scared," Buffy pointed out. Gesturing at the three Havchornom in front of her. "And the only people who aren't scared of getting shot when there's a great big huge gun stuck in their faces… are the ones who know that they're not  _actually_ in any danger."

Jenny paused.

The Havchornom just smiled, with jagged, sharp teeth.

"So what's the gimmick?" Buffy demanded of them.

"Our future selves will reach back and manipulate this moment so it goes in our favor," the Havchornom replied. They gestured towards Jenny. "The Gallifreyan should know better."

Jenny frowned.

Lowered the gun.

"You can manipulate time?" Jenny asked. Her eyes drifted to the image in the center of the table, of the Doctor, Seo, and Jack. "The catastrophe. All those planets, across all those different times. And one moment when it all…" She shuddered. "What did Dad, Seo, and Jack do?"

"Ah," said one of the Havchornom. "The Gallifreyan's worked some of it out, at last."

Buffy looked between the Havchornom and Jenny.

Feeling lost.

"But not all," another Havchornom continued. "You still blame us for the catastrophe."

Jenny shook her head. "You mean you're  _not_  responsible for the catastrophe?"

"We must feed to renew our strength," the Havchornom said. "Large temporal manipulations across the Gateway are still beyond us. We could not create the catastrophe if we wanted to. But the fear and turmoil caused by the catastrophe, amplified by the conduit Buffy Summers, will give us the strength we need to open the Gate and return."

"Yeah, good luck with that," Buffy snapped back. She surged forwards, grabbing one of the Havchornom up by the neck and slamming him against the wall. "You used me to put my daughter in danger. I don't get what this whole 'catastrophe' thing is, or what the hell you guys are talking about, but you're so  _not_  using me to unleash hell onto an unsuspecting universe!"

Jenny stared at them.

Suddenly silent.

"You can't harm us," said the Havchornom Buffy was threatening. "We manipulate the recent past. We can always create something to our advantage, to gain the upper hand in any situation."

"That doesn't work if your future selves are dead!" Buffy shouted. Reaching down for her concealed knife. "And if you don't tell me how to save Seo, I'm gonna cut you down to—!"

She paused.

Then swore, as she realized she'd already lost the knife, earlier.

"Okay, I get it, manipulate the recent past," Buffy said. Mind racing, as she stepped away from the Havchornom. "So I'm guessing if I try to punch you, you'd just alter the events of my recent past so I got a broken arm or whatever, and couldn't."

The Havchornom nodded, smiles on their faces.

"And your injuries, within the chamber, are shared with your daughter," said a Havchornom behind Buffy. "Any broken arm you got, due to your aggression right now, would only harm her, earlier."

"Yeah, yeah, I can take a hint," Buffy grumbled. She backed towards Jenny, still set in a fighting position. "But if you think I'm gonna get you through the Gate, you've so got another… thing…"

Buffy stopped.

Then turned around, to face Jenny. Who'd gone very pale. And very quiet.

"Jenny?" Buffy asked.

Jenny blinked. Then tucked the gun under her arm, and turned. "Let's go."

"What? But these guys are still using their spores to end the universe and stuff!" Buffy insisted. "We're so not about to—!"

The ceiling collapsed, just in front of them. Weakened by the vaporization of the wall.

Their exit was blocked.

Jenny gritted her teeth. Then spun back around, to face the Havchornom. "You think you're so clever, don't you?"

"Tell Buffy Summers the truth," the Havchornom said. "Tell her what you've worked out."

Jenny instead raised up her gun, to fire at them.

But the gun malfunctioned, and died in her hands.

"Tell her," another Havchornom hissed, creeping towards them like a predator stalking his prey. "Tell her what she should already know."

"So you can have the satisfaction of feeding off her misery?" Jenny shook her head. "I don't think so."

Buffy felt fear rising up in her throat.

The smiles on the Havchornom's faces growing wider, as they felt her fear mount.

"What… are you talking about?" Buffy said, struggling to control her emotions. "What's going on?"

"Just leave her alone," Jenny told the Havchornom. "You're going to get enough from her when she finds out. You don't have to rub it in."

"Rub what in?!" Buffy glared at them. "Is anyone going to tell me what you're talking about?!"

"We manipulate the recent past," said one of the Havchornom, coming towards Buffy. "Even outside the Gate, to some extent. You agreed to join us in our manipulations."

"Yeah, because you said I can save…" Buffy stopped. Then looked over at Jenny. "Wait. The Havchornom manipulate the…  _past_ , outside the Gate?"

Jenny didn't answer.

"What happens next to Jack, the Doctor, and Seo… it's already happened," Buffy realized. "Jenny stepped into this time zone to save me. We're both involved — we can't go back in time to Ariffildos and change things, anymore."

The Havchornom gave coarse laughs.

"But that's fine," Buffy decided. "The Doctor's there. He'll figure everything out and save the world without batting an eye! It's not like…"

"You think you can distract us while the Doctor saves the day?" said one Havchornom.

"Stupid little human," said another. "The catastrophe looms. What do you think our game really was?"

Buffy glanced back at the center of the table.

The Doctor sharing his theories about the nature of the catastrophe with everyone else.

"Your spores and monsters and stuff have nothing to do with the catastrophe," Buffy realized. "It was all a distraction. A way for you guys to feed and make sure the Doctor can't outsmart you before the real catastrophe happens. And you gain enough power, feeding off that, to exit the Gate."

The Havchornom applauded Buffy.

"The human has a slow mind," the Havchornom noted. "But she does get there in the end."

"The catastrophe's already happened, hasn't it?" Jenny guessed. "It happened shortly after I got here, when I was still trying to track down Buffy." She took a long, deep breath. "What is it?"

"Can't you guess?" said one Havchornom.

"You guessed before," said another. "It's why you were so frightened to go to Ariffildos in the first place."

Buffy still felt totally lost.

"Look, you're gonna have to give us way more information if you want us to guess what destroyed the future," Buffy told them. "I know all the universal catastrophes. Hellmouths opening, portals being created, or…" Her heart raced. "Is it Seo? Did she go into weapon-mode again?"

"There was no one catastrophic thing that destroyed all those planets," Jenny said, very quietly. "That… isn't how it happened."

Buffy turned to Jenny.

"I told you — I did the research," Jenny said. "I thought it was like you said — one villain arising, or one evil force being unleashed or… one big bang that destroyed everything." She shook her head. "But… that wasn't what destroyed the future."

"Not a new presence," said the Havchornom. "Just the absence of two sisters from history."

Buffy felt something inside herself tighten. "No…"

"That's why I didn't want to go to Ariffildos, in that year, at that time," said Jenny. "Because that's where time changes. So that Seo and I are killed. For good."


	11. Chapter 11

Jack leapt forwards, shoving the Doctor out of the way as the staser blast struck him full in the chest.

He died.

Seo took advantage of the distraction to surge forwards, kicking the staser out of the Master's hands and swinging to punch him across the jaw. He ducked out of the way of the punch, eyes shining yellow, as he hissed at her like a cat.

The Doctor knew he had no choice.

Focused his mind, hard as he could, until the Master popped out of existence, and vanished into the air.

Seo spun around, eyes narrowed. "Why didn't you do that sooner?!"

The Doctor got back to his feet. Waving at the air, where the green blobs had shrunk yet again. "The Master came with the TCE," he said. "Get rid of one, and you get rid of the other."

Seo squinted at the air.

As the blobs vanished.

"Oh."

"Still, in terms of good news," the Doctor decided, picking up the gizmo from where Seo had dropped it, "if that's the best the Havchornom can throw at us, they're clearly not trying very hard. Perhaps they can't quite reach in and affect this universe properly, when they're stuck outside—"

"Can you use me to stop it?" Seo asked.

The Doctor looked over at her.

"If they're using me to reach into the universe and control their spores," Seo reasoned, "there must be something clever we could do to reverse it. Sweep all the spores from this whole galaxy up and send them back where they belong."

The Doctor stared at her.

For a long time.

A sad, long stare, as if he were looking deep into time and couldn't face the answer he saw in its depths.

Then he grinned at her, and turned around. "Nope. Can't do it."

He fixed his eyes back on his little box of tricks, starting to tweak and alter it.

"I was back on Earth," Seo continued, ignoring his assertions, "and someone was trying to use me to come through into our reality. There was this sort of… contraption they used, to shift the focus to somewhere else, but still use my energies to—"

"Nope," the Doctor cut in.

Walking a little further away, in hopes he wouldn't hear her.

"But if we used one of the spores, we could project it back across the link," Seo said, racing after him, "and use it to vacuum up all the other spores out of this entire reality! It's a brilliant—"

"Seo, do you  _ever_  stop and think about your own mortality before you enact your brilliant plans?!" the Doctor interrupted, a bit irritated. He waved the device at her. "Because I won't be around to save you forever. And Jack doesn't exactly have the cleanest track record."

Seo stopped talking.

Went very still.

"You're one person, draining a group of very hostile Havchornom spores out of an entire galaxy," the Doctor said. "I know how hard it is for you to just control a completely normal dimensional portal. Add something like this into the mix… and there's no way you'd ever survive."

Seo looked away.

A little embarrassed.

The Doctor sighed. Then put a hand on her shoulder. "It wasn't your fault."

Seo looked back at him.

"What happened to your mum," said the Doctor. "And what happened to you — against the Cybermen. It wasn't your fault. You don't have to keep throwing yourself into these kinds of situations as some sort of… penance."

Seo's lower lip trembled.

"Your mum once told me that she thought the best heroes are the ones who know when to run away," the Doctor said. "And when they have no choice but to stay and fight." He looked deep into her eyes. "You don't have to nearly kill yourself to prove you're you. Or worthy of holding up your mum's legacy. She'd never have wanted that."

"I just want to put things right," Seo whispered.

"We will," the Doctor assured her. "But let's keep you alive while we do it. Agreed?"

Behind them, Jack gasped back to life.

Sat upright.

Then noticed the Doctor and Seo, over by themselves, speaking in hushed voices. "I miss a father-daughter moment?" he asked, jumping to his feet. "Or did I just miss the plan, the climax, and the grand finale?"

The Doctor looked up.

Grinned.

"Actually, we were just talking about how whoever sent these spores back to where they came from would almost certainly die," the Doctor explained. He stepped forwards, waving at Jack. "But if they can't get inside your head properly, Jack… I think we've found just the man we need!"

* * *

Buffy felt like her whole world was collapsing, around her. As she heard the truth about the catastrophe.

"I can stop it," she said. "I  _have_  to be able to…!"

"But it's already happened," said the Havchornom. They waved at the desk.

And the image in the center changed.

To show the Doctor, Seo's hand held tightly in his, shouting, "Seo, run!" The mad sprint for the TARDIS. And then…

Two shots.

And two bodies falling to the ground. Not moving. Not regenerating. Just… dead.

"No," Buffy breathed.

Feeling that horrible, sinking, gnawing scream racing up into her throat.

Everything she'd done! All those horrible years in Hell, struggling with one single goal in mind! Everything she'd had to endure, because she knew she needed to…!

"Stop it," Buffy said. Then raced at the Havchornom, grabbing one by the shoulders and shaking him. "Manipulate the past! Undo it! Get Seo back!"

"Someone already did," Jenny said. Her eyes lingering on the projection. "I'm supposed to be there, too. When you sent your letter… you saved my life."

Buffy paused.

Remembering Terazina… saying that Buffy's letter might save a life…

A  _single_  life…

"You placed yourself within the time stream, Gallifreyan," the Havchornom informed Jenny, "when you came to rescue Buffy Summers. You cannot now go back to Ariffildos and save your sister. Your actions would be paradoxical."

Buffy stared at Jenny.

Who looked away.

"I know I should have gone to save her," Jenny said. "But… I didn't want to die."

Buffy didn't have any words to say.

As she felt everything she ever knew or understood or loved crumbling away from her in an instant. And couldn't deal with it.

"I know you'll blame me," Jenny said. "And maybe you're right. But there was nothing I could do." Her hands shook. "Ariffildos was a trap. I needed to find some way to find out about the trap, then enter the timestream and stop it before it was sprung. And I thought… when I got your letter…"

She paused.

Then sighed, slouching in place. "I'm sorry."

Buffy didn't care if Jenny was sorry. She was so sick of people with massive guilt complexes trying to take responsibility for things that were none of their damn faults.

Buffy's eyes narrowed on the Havchornom.

"You," Buffy growled. "Murdered. My daughter."

The Havchornom tittered.

"We haven't done anything," one said. "We didn't cause the catastrophe. Just fed off it."

"You distracted the Doctor from figuring it out!" Buffy said. Pointing to the center of the table. "You made the Doctor and Seo and Jack think that the worst was over with that universe-cracking-and-falling-apart stuff, so they wouldn't realize the actual catastrophe would happen afterwards! You…!"

She felt her voice crack.

And had to lower it, to remain steady.

"You gave me hope," said Buffy, her voice very low, "just to get a juicy meal when that hope died, and I found out the truth."

She spun around, grabbing up Jenny's great big gun.

"A Cacotel-Mega 4000," Buffy commented, analyzing it. "Very bling. One of these fell through the rift, once, in Cardiff. I used it to kill the Unbeatable Kwazack and his Demon Hordes."

"The gun doesn't work," said a Havchornom.

"And anything you do, now, we can reach back in time and undo," said another Havchornom. "Your emotions feed us. You are powerless."

"That was your plan, yeah," Buffy agreed. Tearing off the side of the gun. "But you were expecting to feed off the pain and loss the universe felt over  _Jenny's_ death, too. And since Jenny's here, and still alive — you're at half-power."

"Even half-power is enough," said the Havchornom, "to handle one Slayer."

"One Slayer…  _and her friends?_ " Buffy asked.

The Havchornom's heads all turned, at the sound of breaking glass. Stared, in horror, as they realized Jenny had snuck over while they weren't looking.

And just shattered their crystal ball.

"Sorry, was that crystal ball important?" Jenny asked.

"You… can't hope to defeat us," the Havchornom stuttered, stepping back a little. "Our spores carry our essence. While the spores remain in the outside universe…"

"That's what I said," Buffy interrupted. " _Friends_. Like the Doctor."

* * *

"Is it working?" Seo asked, racing over to the other side of the machine. She glanced at Jack, cringing. "Are you going to be all right, Jack?"

"Can't get rid of me that easily, kid," said Jack.

The Doctor ramped up the machine, and Jack was enveloped by a brilliant white light. "Almost, but… just for good measure…" He spun around. Clapped Seo on the back. "Care to do the honors?"

Seo stuck her finger on the pad, gingerly.

Concentrating.

Jack screamed, as the light grew in intensity. Frying him from the inside out.

"Sorry!" Seo said. "Just a little bit—"

"Don't get distracted!" the Doctor urged her. "Lots of power, remember? If you don't control it, we'll get a feedback loop. Burn you out forever."

Seo focused her mind.

And all the powers deep down inside of her.

"That's it!" the Doctor cried, with a grin. "There they all go. Back to where you came from, little spores!"


	12. Chapter 12

**Notes for the Chapter:**

> Sorry about the lack of update yesterday. I was completely swamped at work and forgot.
> 
> Next up... the final story. "Reunion."
> 
> Enjoy.

 

The Havchornom screamed and writhed, as the energy flow was suddenly redirected.

Infecting  _them_  with horror and terror and fear — as if those emotions had originated within themselves. Tearing them apart instead of feeding and sustaining them.

"This will achieve nothing!" the Havchornom cried. "All you'll do, by killing us, is place the Doctor in danger, too!"

"Oh, yeah, like  _that_  threat's gonna work," Buffy said. Shaking up the gun. "I saw that projection. The Doctor got shot just like Seo. If she didn't survive, neither will he."

"You don't under—!" The Havchornom began.

"Just  _don't_  even  _start_!" Buffy screamed, something deep down inside snapping. "You murdered my daughter! You get that? You  _killed_  her! And if Seo's dead — you're gonna die, too."

Buffy's voice lowered, as she stopped shaking the gun.

"And — just so you know," Buffy added. "That gun in Cardiff? Also broken. That didn't stop me."

She threw the gun into the fire, then raced for the door. Jenny close on her heels, just behind, shouting at her that didn't she realize the chemical reactions she'd just induced by rupturing different areas would result in…?!

The whole house blew up, behind them.

Buffy glancing back over her shoulder at the Havchornom, their smoking husks vanishing into nothingness, as they were destroyed.

"You killed them all," Jenny said.

"Seo is dead," said Buffy, "and there's nothing I can do to save her." She got up from the ground, dusting herself off. "They deserved a lot worse."

* * *

Seo lingered by the Doctor, as he scanned the air with his little spore-detection device.

"All gone," the Doctor confirmed. He grinned down at her. "Very good."

Seo stole a glance at Jack.

"Will he be all right?" Seo asked.

The Doctor tucked away his gadget. "Oh, fine," he assured her. "Might take him a day or so to recover. But all-in-all, crisis averted. The future's been saved."

Seo nodded. Her eyes fixed on Jack.

She didn't seem placated.

"He will be fine," the Doctor insisted.

"I hurt him, though," Seo said. She glanced back at her father. "I don't like it when people are in pain. It's why, the moment I saw Jack again, I had to—"

"Take him with you," the Doctor said. "I know."

He headed back to his TARDIS, letting Seo trail after him. So he could double-check what they'd just done, make sure that it had actually altered the future the way he expected.

"You really do love people strongly, don't you?" the Doctor said, turning down a back-alley.

"I… get attached," Seo said, her cheeks growing red. "Clingy. I think I have some abandonment issues."

The Doctor laughed. "I tried to make you hate me, to stop you going to the Irkoli Empire on my behalf," he reminded her. "I was rotten to you. Miserable. But for some reason… you still love me. Just as much as you always have."

"You're my father," said Seo. As if this were enough.

"I'm not, technically," the Doctor said.

Seo shrugged.

And the Doctor reached out, to squeeze her hand. "Your mum was just the same," he said. "It's why she protected people. Because she loved them all so strongly. Didn't matter if it was friends, family, memory-implanted not-quite-sisters. She loved. So she gave them everything."

Seo looked up at him.

"You're more like her than you know," the Doctor said. "She'd be proud."

"Are you proud?" said Seo.

"Oh, always! Did you ever doubt…?"

A throat cleared, just behind them.

Seo and the Doctor turned, to find Jack standing there, a blaster in his hand and an easy smile on his face.

The Doctor gripped Seo's hand a little tighter.

As, a little confused, Seo asked, "Jack?"

"Not quite," the Doctor breathed.

Jack pointed the blaster straight at them. "Sorry to disappoint, cuties," he said. "But there are no Jacks here."

The Doctor turned, dragging Seo after him, as he sprinted for the TARDIS. "Seo, run!"

"Nothing personal," said not-quite-Jack. "But business is business."

And he fired two shots.

Seo screamed.

* * *

Back in Jenny's ship, Buffy stood. Staring at the screen, upon which she'd found and was currently displaying the front page of the newspaper on Ariffildos — complete with pictures and big, bold text, explaining Seo's death.

Jenny, meanwhile was frantically trying to control her ship, and jettison them out of the Gate. The ship shook and rattled, the metal groaning and searing under the strain.

Buffy didn't notice.

Just kept staring.

"And… made it," Jenny announced, with a breath of relief, as the readings stabilized, and the view outside her ship reverted to the familiar starscape of their home universe. Jenny turned to Buffy, triumphant. "Out of a Gate that's impossible to cross, without opening it or letting any bits of Hell out. What do you think about…?"

Jenny paused.

As she saw Buffy still staring at that headline.

"Buffy…" said Jenny, crossing over towards her. "I'm sorry. There's nothing I can do."

"I… know," Buffy whispered. A deep shudder ran through her. "Laws of time causality whatever stuff. I get it."

It looked, however, like Buffy only said the words aloud to convince herself they really were true. She still was seconds around from saying to hell with the universe and jumping in anyways.

She took a long, deep breath. Her hands shaking.

"You can't get her back," Buffy whispered to herself. Voice trembling. "Any more than the Doctor could save his own world. Time can't be rewritten."

Jenny stopped in her tracks.

Pulled out that letter, with the smudged ink and desperate words. Her eyes glued to its surface, as she thought about everything Buffy just said.

Then smiled.

"Actually," Jenny decided, spinning around and launching herself back at the controls to her ship, "on second thought — let's do it!"

Buffy snapped her head up. "What?!"

Jenny was already flipping and switching, jerking open panels to tear out fail safe sections of her ship and ignoring countless warning lights.

"Ariffildos, Year of Robert, 35," Jenny announced. Using her boot to smash one of the temporal fail safe devices she'd installed a while back. "Take two." The whole thing sparked in her face, and she waved away the smoke. "So what if it's already happened and you're already sort of there? We've got a time machine, why not…?"

Buffy launched herself forwards, grabbing Jenny by the arm.

Stared into Jenny's eyes.

"Seo caused the catastrophe just by showing up there and trying to stop it," said Buffy. "You're supposed to die, too. The only thing you'll do, by following her to Ariffildos, is to make it a double-catastrophe."

"Not if I'm strategic," Jenny countered.

Buffy shook her head. "And whoever killed Seo and your dad will be prepared for your strategies," she insisted. "I mean, you said yourself that this was a trap. Anyone who knows you at all would figure out that you'd do the research while Seo just jumped in. There's some part of this whole plot that involves you, Jenny, and it's not going to be simple!" She glanced back over her shoulder. Her eyes dull. "I've lost my daughter. I'm not going to let you… wind up… in that newspaper…"

Buffy trailed off.

Her face sinking into sudden thought.

Then her eyes went wide, and her breath caught in her throat.

"They knew you'd do the research," Buffy said. "And those Havchornom threatened the Doctor's life when I first started defying them, which wouldn't happen if he was already…" A small laugh passed through her lips. "Oh, God! Why didn't I catch that?"

"What…?"

Buffy pulled Jenny away from the flight controls of her ship. "They're not dead, yet, Jenny," said Buffy. She pointed at the newspaper. "I told you someone knew you'd do the research! Look at that paper. It's a fake — specifically for you to find!"

Jenny blinked.

Then realized… Buffy was right.

"How did I not catch that?" Jenny asked herself.

Buffy swung her around, looking deep into her eyes. "You didn't catch it because you were never supposed to," she said. "You said it yourself. Ariffildos is where you and your sister die — but  _not_ where the Doctor dies. Why? Because whatever kills my daughter—"

"—hasn't happened, yet," said Jenny. "It's something involving me. Something that kills my sister and me, while Dad manages to escape." She looked back at the newspaper. "I was never supposed to be on Ariffildos. Someone knew I'd be too scared to go. This is all designed to lure me in… so I die, anyways."

"Yes."

"Then receiving your letter changed nothing," said Jenny. "It just got me deeper in the trap."

"That's right, my letter changed—" Buffy began to confirm. But stopped.

As something occurred to her.

"No," said Buffy. Thinking hard. "When you came to rescue me… those Havchornom really  _were_  at reduced power. And Sineya said…"

One single act of kindness could change the course of history.

Could release Buffy from hell.

Maybe even… stop two sisters from dying.

"That letter," Buffy realized, "didn't  _stop_  you from falling into the trap. It just made sure…  _I_  was around, when you fell into it."

"You?"

"Yes! You, the Doctor, Jack, Seo — you're all wrapped up in this future where everyone dies and everything gets destroyed," Buffy said. "But  _I'm_  not. That's what Terazina did by giving you my letter. She gave you guys  _me_."

Jenny frowned.

"So tell me everything you know about this dead-future, Ariffildos stuff," Buffy demanded, leaning back against the hull of the space ship. "Because whatever time or history says… while I'm around, you're not gonna die, Jenny. And neither is Seo. I promise."


End file.
